Light-emitting device and apparatus including the same

ABSTRACT

A light-emitting device and a method of manufacturing the same are provided. The light-emitting device may include a first electrode, a second electrode, and an interlayer located between the first electrode and the second electrode. The interlayer may include an emission layer that includes a first material, a second material, and a third material. The first material may include an inorganic semiconductor compound, an inorganic insulator compound, or any combination thereof. The second material may include a lanthanide metal. The third material may include an organic compound. An apparatus including the light-emitting device is provided.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and benefits of Korean PatentApplication No. 10-2020-0023838 under 35 U.S.C. § 119, filed on Feb. 26,2020, in the Korean Intellectual Property Office, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND 1. Technical Field

Embodiments relate to a light-emitting device and an apparatus includingthe same.

2. Description of the Related Art

Light-emitting devices are a device in which electrical energy isconverted into light energy. Examples of such light-emitting devicesinclude organic light-emitting devices using organic materials for anemission layer, quantum dot light-emitting devices using quantum dotsfor an emission layer, and the like.

In a light-emitting device, a first electrode is disposed on asubstrate, and a hole transport region, an emission layer, an electrontransport region, and a second electrode are sequentially formed on thefirst electrode. Holes provided from the first electrode may move towardthe emission layer through the hole transport region, and electronsprovided from the second electrode may move toward the emission layerthrough the electron transport region. Carriers, such as holes andelectrons, recombine in the emission layer to produce excitons. Theseexcitons transit from an excited state to a ground state to therebygenerate light.

SUMMARY

Provided is a light-emitting device including an inorganic material andan organic material in an emission layer and an apparatus including thesame.

Aspects of the invention will be set forth in part in the descriptionwhich follows and, in part, will be apparent from the description, ormay be learned by practice of the embodiments of the disclosure.

In an embodiment, a light-emitting device may include a first electrode,a second electrode, and an interlayer located between the firstelectrode and the second electrode. The interlayer may include anemission layer that may include a first material, a second material, anda third material. The first material may include an inorganicsemiconductor compound, an inorganic insulator compound, or anycombination thereof. The second material may include a lanthanide metal.The third material may include an organic compound.

In an embodiment, the first material may include an alkali metal halide,an alkaline earth metal halide, a lanthanide metal halide, a transitionmetal halide, a post-transition metal halide, a tellurium, a lanthanidemetal telluride, a transition metal telluride, a post-transition metaltelluride, a lanthanide metal selenide, a transition metal selenide, apost-transition metal selenide, or any combination thereof. The secondmaterial may include lanthanum (La), cerium (Ce), praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or any combinationthereof. The third material may include an organic fluorescent dopantcompound, an organometallic phosphorescent dopant compound, an organicdelayed fluorescence dopant compound, or any combination thereof.

In an embodiment, the first material may include NaI, KI, RbI, CsI,NaCl, KCl, RbCl, CsCl, NaBr, KBr, RbBr, CsBr, MgI₂, CaI₂, SrI₂, BaI₂,MgCl₂, CaCl₂), SrCl₂, BaCl₂, MgBr₂, CaBr₂, SrBr₂, BaBr₂, EuI₃, YbI₃,SmI₃, TmI₃, EuI₂, YbI₂, SmI₂, TmI₂, EuCl₃, YbC₃, SmCl₃, TmCl₃, EuBr₃,YbBr₃, SmBr₃, TmBr₃, AgI, CuI, NiI₂, CoI₂, BiI₃, PbI₂, SnI₂, Te, EuTe,YbTe, SmTe, TmTe, EuSe, YbSe, SmSe, TmSe, ZnTe, CoTe, ZnSe, CoSe,Bi₂Te₃, Bi₂Se₃, or any combination thereof.

In an embodiment, the first material may include KI, RbI, CsI, CuI, orany combination thereof.

In an embodiment, the second material may include Yb, Tm, Sm, Eu, Er, orany combination thereof.

In an embodiment, a volume of the first material may be greater than orequal to a volume of the second material.

In an embodiment, the first electrode may be an anode, the secondelectrode may be a cathode, and the interlayer may further include atleast one of a hole transport region located between the first electrodeand the emission layer and an electron transport region located betweenthe emission layer and the second electrode. The hole transport regionmay include a hole injection layer, a hole transport layer, an electronblocking layer, or any combination thereof. The electron transportregion may include a hole blocking layer, an electron transport layer,an electron injection layer, or any combination thereof.

In an embodiment, the hole injection layer may include a fourth materialand a fifth material, the fourth material and the fifth material, andthe fourth material and the fifth material may be different from eachother. The fourth material may include a lanthanide metal halide, atransition metal halide, a post-transition metal halide, a tellurium, alanthanide metal telluride, a transition metal telluride, apost-transition metal telluride, a lanthanide metal selenide, atransition metal selenide, a post-transition metal selenide, or anycombination thereof. The fifth material may include a hole transportorganic compound, an alkali metal halide, an alkaline earth metalhalide, a lanthanide metal halide, or any combination thereof.

In an embodiment, the fifth material may include a hole transportorganic compound, and the volume ratio of the fourth material to thefifth material may be in a range of about 1:99 to about 20:80.

In an embodiment, the fifth material may include a post-transition metalhalide, an alkali metal halide, an alkaline earth metal halide, alanthanide metal halide, or any combination thereof, and the volumeratio of the fourth material to the fifth material may be in a range ofabout 0:100 to about 50:50.

In an embodiment, the electron injection layer may include a sixthmaterial, and the sixth material may include an alkali metal halide, analkaline earth metal halide, a lanthanide metal halide, or anycombination thereof.

In an embodiment, the electron injection layer may consist of the sixthmaterial.

In an embodiment, the electron injection layer may further include aseventh material, and the sixth material and the seventh material may bedifferent from each other. The seventh material may include an alkalimetal, an alkaline earth metal, a lanthanide metal, or any combinationthereof.

In an embodiment, the sixth material may be represented by Formula X,and the seventh material may be represented by Formula Y:A_(n)B_(m)  <Formula X>C  <Formula Y>

In Formulae X and Y,

-   -   A and C may each independently include an alkali metal, an        alkaline earth metal, a lanthanide metal, or any combination        thereof,    -   B may be a halogen,    -   n and m may each independently be an integer of 1 or more that        makes the sixth material neutral, and    -   A and C may be different from each other.

In an embodiment, the hole transport layer may be in direct contact withthe emission layer, and the hole transport layer may include an eighthmaterial and a ninth material. The eighth material and the ninthmaterial may be different from each other, the eighth material mayinclude at least one hole transport organic compound, and the ninthmaterial may include an alkali metal halide, an alkaline earth metalhalide, a lanthanide metal halide, or any combination thereof.

In an embodiment, the electron transport layer may be in direct contactwith the emission layer, and the electron transport layer may include atenth material and an eleventh material. The tenth material and theeleventh material may be different from each other, the tenth materialmay include at least one electron transport organic compound, and theeleventh material may include an alkali metal halide, an alkaline earthmetal halide, a lanthanide metal halide, or any combination thereof.

In an embodiment, a light-emitting device may include a first electrode,a second electrode facing the first electrode, light-emitting unitslocated between the first electrode and the second electrode, and chargegenerating units each located between neighboring ones of thelight-emitting units. Each of the light-emitting units may include anemission layer, and at least one of the emission layers may include afirst material, a second material, and a third material. The firstmaterial may include an inorganic semiconductor compound, an inorganicinsulator compound, or any combination thereof. The second material mayinclude a lanthanide metal. The third material may include an organiccompound.

In an embodiment, each of the charge generating units may include ann-type charge generating layer and a p-type charge generating layer.

In an embodiment, the n-type charge generating layer may include atwelfth material and a thirteenth material. The twelfth material mayinclude an alkali metal, an alkaline earth metal, a lanthanide metal,transition metal, a post-transition metal, or any combination thereof.The thirteenth material may include an electron transport organiccompound. The p-type charge generating layer may include a fourteenthmaterial and a fifteenth material. The fourteenth material may include ahole transport organic compound, an inorganic insulator compound, or anycombination thereof. The fifteenth material may include an inorganicsemiconductor compound.

In an embodiment, an apparatus may include a thin-film transistor andthe light-emitting device. The thin film transistor may include a sourceelectrode, a drain electrode, and an activation layer. The firstelectrode of the light-emitting device may be electrically connectedwith one of the source electrode and the drain electrode of thethin-film transistor.

In an embodiment, the apparatus may further include a color filter, andthe color filter may be located on a path through which light from thelight-emitting device is emitted.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the embodimentsof the disclosure will be more apparent from the following descriptiontaken in conjunction with the accompanying drawings, in which:

FIGS. 1 to 4 show schematic cross-sectional views of a light-emittingdevice according to an embodiment; and

FIG. 5 shows a schematic cross-sectional view of a tandem light-emittingdevice according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, theembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the description.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items. For example, “A and/or B”may be understood to mean “A, B, or A and B.” The terms “and” and “or”may be used in the conjunctive or disjunctive sense and may beunderstood to be equivalent to “and/or”. Throughout the disclosure, theexpression “at least one of A, B, or C” may indicate only A, only B,only C, both A and B, both A and C, both B and C, all of A, B, and C, orvariations thereof.

The term “at least one of” is intended to include the meaning of “atleast one selected from the group consisting of” for the purpose of itsmeaning and interpretation. For example, “at least one of A and B” maybe understood to mean “A, B, or A and B.” When preceding a list ofelements, the term, “at least one of,” modifies the entire list ofelements and does not modify the individual elements of the list.

As the disclosure can apply various transformations and can have variousexamples, specific examples will be illustrated in the drawings anddescribed in detail in the detailed description. Effects and features ofthe disclosure, and methods of achieving the same will be clarified byreferring to Examples described in detail later with reference to thedrawings. However, the disclosure is not limited to the examplesdisclosed below and may be implemented in various forms.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. The same or corresponding components will bedenoted by the same reference numerals, and thus redundant descriptionthereof will be omitted.

It will be understood that although the terms “first,” “second,” etc.may be used herein to describe various components, these componentsshould not be limited by these terms. These components are only used todistinguish one component from another.

As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be further understood that the terms “comprises”, “comprising”,“includes”, “including”, “contains”, and/or “containing” used hereinspecify the presence of stated features or components, but do notpreclude the presence or addition of one or more other features orcomponents.

It will be understood that when a layer, region, or component isreferred to as being “on” or “onto” another layer, region, or component,it may be directly or indirectly formed on the other layer, region, orcomponent. For example, intervening layers, regions, or components maybe present.

Sizes of elements in the drawings may be exaggerated for convenience ofexplanation. In other words, since sizes and thicknesses of componentsin the drawings are arbitrarily illustrated for convenience ofexplanation, the following embodiments are not limited thereto.

The terms “about” or “approximately” as used herein is inclusive of thestated value and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” may mean within one or morestandard deviations, or within ±20%, 10%, or 5% of the stated value.

It will be understood that when a layer, region, or component isreferred to as being “connected to” another layer, region, or component,the layer, region, or component may be directly connected to the anotherlayer, region, or component, or indirectly connected to the anotherlayer, region, or component as intervening layer, region, or componentis present. For example, it will be understood that when a layer,region, or component is referred to as being “physically connected to”another layer, region, or component, the layer, region, or component maybe directly physically connected to the another layer, region, orcomponent, or indirectly physically connected to the another layer,region, or component as intervening layer, region, or component ispresent. For example, it will be understood that when a layer, region,or component is referred to as being “electrically connected to” anotherlayer, region, or component, the layer, region, or component may bedirectly electrically connected to the another layer, region, orcomponent, or indirectly electrically connected to the another layer,region, or component as intervening layer, region, or component ispresent.

The term “interlayer” as used herein refers to a single layer and/or alllayers between a first electrode and a second electrode of alight-emitting device. A material included in the “interlayer” may be anorganic material and/or an inorganic material.

The expression “(an interlayer) includes at least one compoundrepresented by Formula 1” as used herein may include a case in which“(an interlayer) includes identical compounds represented by Formula 1”and a case in which “(an interlayer) includes two or more differentcompounds represented by Formula 1”.

In the specification, the term “Group” refers to a group on the IUPACPeriodic Table of Elements.

The term “inorganic semiconductor compound” as used herein refers to anycompound being an inorganic material and having a band gap of less than4 eV. In an embodiment, an inorganic semiconductor compound may includea lanthanide metal halide, a transition metal halide, a post-transitionmetal halide, a tellurium, a lanthanide metal telluride, a transitionmetal telluride, a post-transition metal telluride, a lanthanide metalselenide, a transition metal selenide, a post-transition metal selenide,or any combination thereof. In an embodiment, the inorganicsemiconductor compound may include EuI₂, YbI₂, SmI₂, TmI₂, AgI, CuI,NiI₂, CoI₂, BiI₃, PbI₂, SnI₂, Te, EuTe, YbTe, SmTe, TmTe, EuSe, YbSe,SmSe, TmSe, ZnTe, CoTe, ZnSe, CoSe, Bi₂Te₃, Bi₂Se₃, or any combinationthereof.

The term “inorganic insulator compound” as used herein refers to anycompound being an inorganic material and having a band gap of 4 eV ormore. In an embodiment, the inorganic insulator compound may include analkaline earth metal halide, a lanthanide metal halide, or anycombination thereof. An inorganic insulation compound may include NaI,KI, RbI, CsI, NaCl, KCl, RbCl, CsCl, NaF, KF, RbF, CsF, MgI₂, CaI₂,SrI₂, BaI₂, MgCl₂, CaCl₂), SrCl₂, BaCl₂, MgF₂, CaF₂, SrF₂, BaF₂, EuI₃,YbI₃, SmI₃, TmI₃, EuCl₃, YbCl₃, SmCl₃, TmCl₃, EuF₃, YbF₃, SmF₃, TmF₃, orany combination thereof.

The term “alkali metal halide” as used herein refers to a compound inwhich alkali metal and a halogen are ionically bonded. In an embodiment,the alkali metal halide may include NaI, KI, RbI, CsI, NaCl, KCl, RbCl,CsCl, NaF, KF, RbF, CsF, or any combination thereof.

The term “alkaline earth metal halide” as used herein refers to acompound in which alkaline earth metal and a halogen are ionicallybonded. In an embodiment, the alkaline earth metal halide may includeMgI₂, CaI₂, SrI₂, BaI₂, MgCl₂, CaCl₂), SrCl₂, BaCl₂, MgF₂, CaF₂, SrF₂,BaF₂, or any combination thereof.

The term “lanthanide metal halide” as used herein refers to a compoundin which a lanthanide metal and a halogen are ionically bonded and/orcovalently bonded. In an embodiment, the lanthanide metal halide mayinclude EuI₂, YbI₂, SmI₂, TmI₂, EuI₃, YbI₃, SmI₃, TmI₃, EuCl₃, YbCl₃,SmCl₃, TmCl₃, EuF₃, YbF₃, SmF₃, TmF₃, or any combination thereof.

The term “transition metal halide” as used herein refers to a compoundin which a transition metal and a halogen are ionically bonded and/orcovalently bonded. In an embodiment, the transition metal halide mayinclude AgI, CuI, NiI₂, CoI₂, or any combination thereof.

The term “post-transition metal halide” as used herein refers to acompound in which a post-transition metal and a halogen are ionicallybonded and/or covalently bonded. In an embodiment, the post-transitionmetal halide may include BiI₃, PbI₂, SnI₂, or any combination thereof.

The term “lanthanide metal telluride” as used herein refers to acompound in which a lanthanide metal and tellurium (Te) are ionicallybonded, covalently bonded, and/or metallically bonded. In an embodiment,the lanthanide metal telluride may include EuTe, YbTe, SmTe, TmTe, orany combination thereof.

The term “transition metal telluride” as used herein refers to acompound in which transition metal and tellurium are ionically bonded,covalently bonded, and/or metallically bonded. In an embodiment, thetransition metal telluride may include ZnTe, CoTe, or any combinationthereof.

The “post-transition metal telluride” as used herein refers to acompound in which post-transition metal and tellurium are ionicallybonded, covalently bonded, and/or metallically bonded. In an embodiment,the post-transition metal telluride may include Bi₂Te₃.

The “lanthanide metal selenide” as used herein refers to a compound inwhich a lanthanide metal and selenium (Se) are ionically bonded,covalently bonded, and/or metallically bonded. In an embodiment, thelanthanide metal selenide may include EuSe, YbSe, SmSe, TmSe, or anycombination thereof.

The term “transition metal selenide” as used herein refers to a compoundin which transition metal and selenium are ionically bonded, covalentlybonded, and/or metallically bonded. In an embodiment, the transitionmetal selenide may include ZnSe, CoSe, or any combination thereof.

The term “post-transition metal selenide” as used herein refers to acompound in which post-transition metal and selenium are ionicallybonded, covalently bonded, and/or metallically bonded compound. In anembodiment, the post-transition metal selenide may include Bi₂Se₃.

The term “alkali metal” as used herein refers to a Group 1 element. Inan embodiment, an alkali metal may be lithium (Li), sodium (Na),potassium (K), rubidium (Rb), or cesium (Cs).

The term “alkaline earth metal” as used herein refers to a Group 2element. In an embodiment, an alkaline earth metal may be magnesium(Mg), calcium (Ca), strontium (Sr), or barium (Ba).

The term “lanthanide metal” as used herein refers to lanthanum and alanthanide element in the Periodic Table of Elements. In an embodiment,a lanthanide metal may be lanthanum (La), cerium (Ce), praseodymium(Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu).

The term “transition metal” as used herein refers to an element thatbelongs to the fourth-row to the seventh-row of the Periodic Table ofElements and belongs to Group 3 to Group 12 of the Periodic Table ofElements. In an embodiment, the transition metal may be titanium (Ti),zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta),chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium(Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co),rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt),copper (Cu), silver (Ag), gold (Au), zinc (Zn), or cadmium (Cd).

The term “post-transition metal” as used herein refers to a metalelement that belongs to the fourth-row to seventh-row of the PeriodicTable of Elements and belongs to Group 13 to Group 17 of the PeriodicTable of Elements. In an embodiment, the post-transition metal may bealuminum (Al), gallium (Ga), indium (In), thallium (Tl), tin (Sn), lead(Pb), bismuth (Bi), or polonium (Po).

The term “halogen” as used herein refers to a Group 17 element. In anembodiment, a halogen may be fluorine (F), chlorine (Cl), bromine (Br),or iodine (I).

[Description of FIG. 1 ]

FIG. 1 is a schematic cross-sectional view of a light-emitting device 1according to an embodiment.

Referring to FIG. 1 , the light-emitting device 1 according to anembodiment includes: a first electrode 110; a second electrode 190; andan interlayer 150 including an emission layer located between the firstelectrode and the second electrode.

The structure of the light-emitting device 1 according to an embodimentof the disclosure and a method of manufacturing the light-emittingdevice 1 will be described in connection with FIG. 1 .

[First Electrode 110]

In FIG. 1 , a substrate may be additionally located under the firstelectrode 110 or above the second electrode 190. The substrate may be aglass substrate or a plastic substrate, each having excellent mechanicalstrength, thermal stability, transparency, surface smoothness, ease ofhandling, and water resistance.

The first electrode 110 may be formed by, for example, depositing orsputtering a material for forming the first electrode on the substrate.When the first electrode 110 is an anode, the material for a firstelectrode may be selected from materials with a high work function tofacilitate hole injection.

The first electrode 110 may be a reflective electrode, asemi-transmissive electrode, or a transmissive electrode. When the firstelectrode 110 is a transmissive electrode, a material for forming afirst electrode may be selected from indium tin oxide (ITO), indium zincoxide (IZO), tin oxide (SnO₂), zinc oxide (ZnO), and any combinationthereof, but embodiments are not limited thereto. In embodiments, whenthe first electrode 110 is a semi-transmissive electrode or a reflectiveelectrode, a material for forming a first electrode may be selected frommagnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al—Li),calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), andany combination thereof, but embodiments are not limited thereto.

The first electrode 110 may have a single-layered structure or amulti-layered structure including two or more layers. For example, thefirst electrode 110 may have a three-layered structure of ITO/Ag/ITO,but the structure of the first electrode 110 is not limited thereto.

[Interlayer 150]

The middle layer 150 is located on the first electrode 110. The organiclayer 150 may include an emission layer.

The interlayer 150 may further include at least one of a hole transportregion located between the first electrode 110 and the emission layerand an electron transport region located between the emission layer andthe second electrode 190.

In an embodiment, the first electrode may be an anode, the secondelectrode may be a cathode, and the interlayer may further include atleast one of a hole transport region located between the first electrodeand the emission layer and an electron transport region located betweenthe emission layer and the second electrode. The hole transport regionmay include a hole injection layer, a hole transport layer, an electronblocking layer, or any combination thereof. The electron transportregion may include a hole blocking layer, an electron transport layer,an electron injection layer, or any combination thereof.

[Hole Transport Region in Organic Layer 150]

The hole transport region may have i) a single-layered structureincluding a single layer including a single material, ii) asingle-layered structure including a single layer including differentmaterials, or iii) a multi-layered structure having multiple layersincluding different materials.

The hole transport region may include a hole injection layer, a holetransport layer, an electron blocking layer, or any combination thereof.

[Hole Injection Layer in Hole Transport Region]

The light-emitting device may include a hole injection layer contacting(e.g., directly contacting) the first electrode.

The hole injection layer may include a fourth material and a fifthmaterial, and the fourth material and the fifth material may bedifferent from each other.

In an embodiment, the fourth material may include a lanthanide metalhalide, a transition metal halide, a post-transition metal halide, atellurium, a lanthanide metal telluride, a transition metal telluride, apost-transition metal telluride, a lanthanide metal selenide, atransition metal selenide, a post-transition metal selenide, or anycombination thereof.

In an embodiment, the volume of the fifth material in the hole injectionlayer may be greater than or equal to the volume of the fourth materialin the hole injection layer.

In an embodiment, the volume percentage of the fourth material in thehole injection layer may be 50% or less.

In an embodiment, the fifth material may include a hole transportorganic compound, an alkali metal halide, an alkaline earth metalhalide, a lanthanide metal halide, or any combination thereof.

The fifth material may include at least one hole transport organiccompound, and the volume ratio of the fourth material to the fifthmaterial may be in a range of about 1:99 to about 20:80.

In an embodiment, the fifth material may include a post-transition metalhalide, an alkali metal halide, an alkaline earth metal halide, alanthanide metal halide, or any combination thereof, and the volumeratio of the fourth material to the fifth material may be in a range ofabout 0:100 to about 50:50. In an embodiment, the volume ratio of thefourth material to the fifth material may be in a range of about0.01:99.99 to about 50:50. In an embodiment, the volume ratio of thefourth material to the fifth material may be in a range of about0.1:99.9 to about 50:50. In an embodiment, the volume ratio of thefourth material to the fifth material may be in a range of about 1:99 toabout 50:50. However, embodiments are not limited thereto.

The term “hole transport organic compound” as used herein refers to anyorganic material having hole transport property.

In an embodiment, the hole transport organic compound may include atleast one selected from m-MTDATA, TDATA, 2-TNATA, NPB(NPD), β-NPB, TPD,spiro-TPD, spiro-NPB, methylated-NPB, TAPC, HMTPD,4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/camphor sulfonic acid (PANI/CSA),polyaniline/poly(4-styrenesulfonate) (PANI/PSS), a compound representedby Formula 201 below, and a compound represented by Formula 202 below:

In Formulae 201 and 202,

-   -   L₂₀₁ to L₂₀₄ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkylene group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenylene group,        a substituted or unsubstituted C₆-C₆₀ arylene group, a        substituted or unsubstituted C₁-C₆₀ heteroarylene group, a        substituted or unsubstituted divalent non-aromatic condensed        polycyclic group, and a substituted or unsubstituted divalent        non-aromatic condensed heteropolycyclic group,    -   L₂₀₅ may be selected from *—O—*′, *—S—*′, *—N(Q₂₀₁)-*′, a        substituted or unsubstituted C₁-C₂₀ alkylene group, a        substituted or unsubstituted C₂-C₂₀ alkenylene group, a        substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkylene group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenylene group,        a substituted or unsubstituted C₆-C₆₀ arylene group, a        substituted or unsubstituted C₁-C₆₀ heteroarylene group, a        substituted or unsubstituted divalent non-aromatic condensed        polycyclic group, and a substituted or unsubstituted divalent        non-aromatic condensed heteropolycyclic group,    -   xa1 to xa4 may each independently be an integer from 0 to 3,    -   xa5 may be an integer from 1 to 10, and    -   R₂₀₁ to R₂₀₄ and Q₂₀₁ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a        substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or        unsubstituted C₆-C₆₀ aryloxy group, a substituted or        unsubstituted C₆-C₆₀ arylthio group, a substituted or        unsubstituted C₁-C₆₀ heteroaryl group, a substituted or        unsubstituted monovalent non-aromatic condensed polycyclic        group, and a substituted or unsubstituted monovalent        non-aromatic condensed heteropolycyclic group.

For example, in Formula 202, R₂₀₁ and R₂₀₂ may optionally be linked toeach other via a single bond, a dimethyl-methylene group, or adiphenyl-methylene group, and R₂₀₃ and R₂₀₄ may optionally be linked toeach other via a single bond, a dimethyl-methylene group, or adiphenyl-methylene group.

In an embodiment, in Formulae 201 and 202,

-   -   L₂₀₁ to L₂₀₅ may each independently be selected from:    -   a phenylene group, a pentalenylene group, an indenylene group, a        naphthylene group, an azulenylene group, a heptalenylene group,        an indacenylene group, an acenaphthylene group, a fluorenylene        group, a spiro-bifluorenylene group, a benzofluorenylene group,        a dibenzofluorenylene group, a phenalenylene group, a        phenanthrenylene group, an anthracenylene group, a        fluoranthenylene group, a triphenylenylene group, a pyrenylene        group, a chrysenylene group, a naphthacenylene group, a        picenylene group, a perylenylene group, a pentaphenylene group,        a hexacenylene group, a pentacenylene group, a rubicenylene        group, a coronenylene group, an ovalenylene group, a        thiophenylene group, a furanylene group, a carbazolylene group,        an indolylene group, an isoindolylene group, a benzofuranylene        group, a benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, and a        pyridinylene group; and    -   a phenylene group, a pentalenylene group, an indenylene group, a        naphthylene group, an azulenylene group, a heptalenylene group,        an indacenylene group, an acenaphthylene group, a fluorenylene        group, a spiro-bifluorenylene group, a benzofluorenylene group,        a dibenzofluorenylene group, a phenalenylene group, a        phenanthrenylene group, an anthracenylene group, a        fluoranthenylene group, a triphenylenylene group, a pyrenylene        group, a chrysenylene group, a naphthacenylene group, a        picenylene group, a perylenylene group, a pentaphenylene group,        a hexacenylene group, a pentacenylene group, a rubicenylene        group, a coronenylene group, an ovalenylene group, a        thiophenylene group, a furanylene group, a carbazolylene group,        an indolylene group, an isoindolylene group, a benzofuranylene        group, a benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, and a        pyridinylene group, each substituted with at least one selected        from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazino group, a        hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclopentenyl group, a cyclohexenyl group, a phenyl group, a        biphenyl group, a terphenyl group, a phenyl group substituted        with a C₁-C₁₀ alkyl group, a phenyl group substituted with —F, a        pentalenyl group, an indenyl group, a naphthyl group, an        azulenyl group, a heptalenyl group, an indacenyl group, an        acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group,        a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl        group, a phenanthrenyl group, an anthracenyl group, a        fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a        chrysenyl group, a naphthacenyl group, a picenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a rubicenyl group, a coronenyl group, an        ovalenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, —Si(Q₃₁)(Q₃₂)(Q₃₃) and —N(Q₃₁)(Q₃₂),    -   wherein Q₃₁ to Q₃₃ may each independently be selected from a        C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a        biphenyl group, a terphenyl group, and a naphthyl group.

In embodiments, xa1 to xa4 may each independently be 0, 1, or 2.

In embodiments, xa5 may be 1, 2, 3, or 4.

In embodiments, R₂₀₁ to R₂₀₄ and Q₂₀₁ may each independently be selectedfrom: a phenyl group, a biphenyl group, a terphenyl group, a pentalenylgroup, an indenyl group, a naphthyl group, an azulenyl group, aheptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenylgroup, a spiro-bifluorenyl group, a benzofluorenyl group, adibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, ananthracenyl group, a fluoranthenyl group, a triphenylenyl group, apyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group,a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenylgroup, a rubicenyl group, a coronenyl group, an ovalenyl group, athiophenyl group, a furanyl group, a carbazolyl group, an indolyl group,an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, adibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolylgroup, a dibenzocarbazolyl group, a dibenzosilolyl group, and apyridinyl group; and

-   -   a phenyl group, a biphenyl group, a terphenyl group, a        pentalenyl group, an indenyl group, a naphthyl group, an        azulenyl group, a heptalenyl group, an indacenyl group, an        acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group,        a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl        group, a phenanthrenyl group, an anthracenyl group, a        fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a        chrysenyl group, a naphthacenyl group, a picenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a rubicenyl group, a coronenyl group, an        ovalenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group, each substituted with at least one selected from        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclopentenyl group, a cyclohexenyl group, a phenyl group, a        biphenyl group, a terphenyl group, a phenyl group substituted        with a C₁-C₁₀ alkyl group, a phenyl group substituted with —F, a        pentalenyl group, an indenyl group, a naphthyl group, an        azulenyl group, a heptalenyl group, an indacenyl group, an        acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group,        a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl        group, a phenanthrenyl group, an anthracenyl group, a        fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a        chrysenyl group, a naphthacenyl group, a picenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a rubicenyl group, a coronenyl group, an        ovalenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, —Si(Q₃₁)(Q₃₂)(Q₃₃) and —N(Q₃₁)(Q₃₂),    -   wherein Q₃₁ to Q₃₃ are the same as described above.

In embodiments, at least one selected from R₂₀₁ to R₂₀₃ in Formula 201may each independently be selected from:

-   -   a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl        group, a dibenzofuranyl group, and a dibenzothiophenyl group;        and    -   a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl        group, a dibenzofuranyl group, and a dibenzothiophenyl group,        each substituted with at least one selected from deuterium, —F,        —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an        amidino group, a hydrazino group, a hydrazono group, a C₁-C₂₀        alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a        cyclohexenyl group, a phenyl group, a biphenyl group, a        terphenyl group, a phenyl group substituted with a C₁-C₁₀ alkyl        group, a phenyl group substituted with —F, a naphthyl group, a        fluorenyl group, a spiro-bifluorenyl group, a carbazolyl group,        a dibenzofuranyl group, and a dibenzothiophenyl group, but        embodiments are not limited thereto.

In embodiments, in Formula 202, i) R₂₀₁ and R₂₀₂ may be linked to eachother via a single bond, and/or ii) R₂₀₃ and R₂₀₄ may be linked to eachother via a single bond.

In embodiments, R₂₀₁ to R₂₀₄ in Formula 202 may each independently beselected from:

-   -   a carbazolyl group; and    -   a carbazolyl group substituted with at least one selected from        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclopentenyl group, a cyclohexenyl group, a phenyl group, a        biphenyl group, a terphenyl group, a phenyl group substituted        with a C₁-C₁₀ alkyl group, a phenyl group substituted with —F, a        naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a        carbazolyl group, a dibenzofuranyl group, and a        dibenzothiophenyl group,    -   but embodiments are not limited thereto.

In embodiments, the compound represented by Formula 201 may berepresented by Formula 201A below:

In embodiments, the compound represented by Formula 201 may berepresented by Formula 201A(1) below, but embodiments are not limitedthereto:

In embodiments, the compound represented by Formula 201 may berepresented by Formula 201A-1 below, but embodiments are not limitedthereto:

In embodiments, the compound represented by Formula 202 may berepresented by Formula 202A below:

In embodiments, the compound represented by Formula 202 may berepresented by Formula 202A-1 below:

In Formulae 201A, 201A(1), 201A-1, 202A, and 202A-1,

-   -   L₂₀₁ to L₂₀₃, xa1 to xa3, xa5, and R₂₀₂ to R₂₀₄ are the same as        described above,    -   R₂₁₁ and R₂₁₂ are the same as described in connection with R₂₀₃,        and    -   R₂₁₃ to R₂₁₇ may each independently be selected from hydrogen,        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclopentenyl group, a cyclohexenyl group, a phenyl group, a        biphenyl group, a terphenyl group, a phenyl group substituted        with a C₁-C₁₀ alkyl group, a phenyl group substituted with —F, a        pentalenyl group, an indenyl group, a naphthyl group, an        azulenyl group, a heptalenyl group, an indacenyl group, an        acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group,        a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl        group, a phenanthrenyl group, an anthracenyl group, a        fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a        chrysenyl group, a naphthacenyl group, a picenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a rubicenyl group, a coronenyl group, an        ovalenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group.

The hole transport region may include at least one compound selectedfrom compounds HT1 to HT39, but compounds to be included in the holetransport region are not limited thereto:

A thickness of the hole injection layer may be in a range of about 0.1nm to about 20 nm. When the thickness of the hole injection layer iswithin the range, satisfactory hole injection characteristics may beobtained without a substantial increase in driving voltage.

[Hole Transport Layer in Hole Transport Region]

The light-emitting device 1 may include a hole transport layercontacting (e.g., directly contacting) the emission layer.

The hole transport layer may include an eighth material and a ninthmaterial. The eighth material and the ninth material may be differentfrom each other. The eighth material may include at least one holetransport organic compound, and the ninth material may include an alkalimetal halide, an alkaline earth metal halide, a lanthanide metal halide,or any combination thereof.

The volume of the eighth material in the hole transport layer may begreater than the volume of the ninth material in the hole transportlayer. In an embodiment, the volume ratio of the eighth material to theninth material in the hole transport layer may be in a range of about99:1 to about 50:50.

A thickness of the hole transport layer may be in a range of about 0.1nm to about 10 nm. When the thickness of the hole transport layer iswithin the range, satisfactory hole transport characteristics may beobtained without a substantial increase in driving voltage.

[Charge-Generation Material in Hole Transport Region]

The hole transport region may further include, in addition to thesematerials, a charge-generation material for the improvement ofconductive properties. The charge-generation material may behomogeneously or non-homogeneously dispersed in the hole transportregion.

The charge-generation material may be, for example, a p-dopant.

In an embodiment, the p-dopant may have a lowest unoccupied molecularorbital (LUMO) energy level of −3.5 eV or less.

The p-dopant may include at least one of a quinone derivative, a metaloxide, and a cyano group-containing compound, but embodiments are notlimited thereto.

For example, the p-dopant may include at least one selected from: aquinone derivative, such as tetracyanoquinodimethane (TCNQ) orF4-2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ);

-   -   a metal oxide, such as tungsten oxide or molybdenum oxide;    -   a transition metal halide such as CuI;    -   a transition metal telluride such as ZnTe;    -   1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN); and    -   a compound represented by Formula 221 below,    -   but embodiments are not limited thereto:

In Formula 221,

-   -   R₂₂₁ to R₂₂₃ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a        substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or        unsubstituted C₁-C₆₀ heteroaryl group, a substituted or        unsubstituted monovalent non-aromatic condensed polycyclic        group, and a substituted or unsubstituted monovalent        non-aromatic condensed heteropolycyclic group, and at least one        selected from R₂₂₁ to R₂₂₃ may have at least one substituent        selected from a cyano group, —F, —Cl, —Br, —I, a C₁-C₂₀ alkyl        group substituted with —F, a C₁-C₂₀ alkyl group substituted with        —Cl, a C₁-C₂₀ alkyl group substituted with —Br, and a C₁-C₂₀        alkyl group substituted with —I.

[Emission Layer in Interlayer 150]

When the light-emitting device is a full-color light-emitting device,the emission layer may be patterned into a red emission layer, a greenemission layer, or a blue emission layer, according to a subpixel. Inembodiments, the emission layer may have a stacked structure of two ormore layers selected from a red emission layer, a green emission layer,and a blue emission layer, in which the two or more layers contact eachother or are separated from each other. In embodiments, the emissionlayer may include two or more materials selected from a redlight-emitting material, a green light-emitting material, and a bluelight-emitting material, in which the two or more materials are mixedwith each other in a single layer to emit white light.

The emission layer may include a first material, a second material, anda third material.

The first material may act as an inorganic host in the emission layer.In an embodiment, the first material itself does not emit light, but thefirst material may substantially transfer excitons to the third materialto help the third material emit light.

The second material may act as a sensitizer in the emission layer. In anembodiment, the second material may enable rapid reverse transition fromthe triplet exciton to the singlet exciton and transfer the singletexciton to the third material. Accordingly, substantially all tripletexcitons and singlet excitons may be delivered to the third material.For example, the efficiency and/or lifespan of the light-emitting devicemay be improved due to the second material.

The third material may act as a light-emitting dopant.

The first material may include an inorganic semiconductor compound, aninorganic insulator compound, or any combination thereof.

For example, the first material may include an alkali metal halide, analkaline earth metal halide, a lanthanide metal halide, a transitionmetal halide, a post-transition metal halide, a tellurium, a lanthanidemetal telluride, a transition metal telluride, a post-transition metaltelluride, a lanthanide metal selenide, a transition metal selenide, apost-transition metal selenide, or any combination thereof.

In an embodiment, the first material may include NaI, KI, RbI, CsI,NaCl, KCl, RbCl, CsCl, NaBr, KBr, RbBr, CsBr, MgI₂, CaI₂, SrI₂, BaI₂,MgCl₂, CaCl₂), SrCl₂, BaCl₂, MgBr₂, CaBr₂, SrBr₂, BaBr₂, EuI₃, YbI₃,SmI₃, TmI₃, EuI₂, YbI₂, SmI₂, TmI₂, EuCl₃, YbCl₃, SmCl₃, TmCl₃, EuBr₃,YbBr₃, SmBr₃, TmBr₃, AgI, CuI, NiI₂, CoI₂, BiI₃, PbI₂, SnI₂, Te, EuTe,YbTe, SmTe, TmTe, EuSe, YbSe, SmSe, TmSe, ZnTe, CoTe, ZnSe, CoSe,Bi₂Te₃, Bi₂Se₃, or any combination thereof.

In an embodiment, the first material may include KI, RbI, CsI, CuI, orany combination thereof, but embodiments are not limited thereto.

For example, the second material may include lanthanum (La), cerium(Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium(Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or anycombination thereof.

In an embodiment, the second material may include Yb, Tm, Sm, Eu, Er orany combination thereof, but embodiments are not limited thereto.

For example, the third material may include an organic fluorescentdopant compound, an organometallic phosphorescent dopant compound, anorganic delayed fluorescence dopant compound, or any combinationthereof.

The organic fluorescent dopant compound may be an organic compound thatmay emit fluorescent light, and may include an arylamine compound or astyrylamine compound.

In an embodiment, the organic fluorescent dopant compound may include acompound represented by Formula 501:

In Formula 501,

-   -   Ar₅₀₁ may be a substituted or unsubstituted C₅-C₆₀ carbocyclic        group or a substituted or unsubstituted C₁-C₆₀ heterocyclic        group,    -   L₅₀₁ to L₅₀₃ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkylene group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenylene group,        a substituted or unsubstituted C₆-C₆₀ arylene group, a        substituted or unsubstituted C₁-C₆₀ heteroarylene group, a        substituted or unsubstituted divalent non-aromatic condensed        polycyclic group, and a substituted or unsubstituted divalent        non-aromatic condensed heteropolycyclic group,    -   xd1 to xd3 may each independently be an integer from 0 to 3,    -   R₅₀₁ and R₅₀₂ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a        substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or        unsubstituted C₆-C₆₀ aryloxy group, a substituted or        unsubstituted C₆-C₆₀ arylthio group, a substituted or        unsubstituted C₁-C₆₀ heteroaryl group, a substituted or        unsubstituted monovalent non-aromatic condensed polycyclic        group, and a substituted or unsubstituted monovalent        non-aromatic condensed heteropolycyclic group, and    -   xd4 may be an integer from 1 to 6.

In an embodiment, Ar₅₀₁ in Formula 501 may be selected from:

-   -   a naphthalene group, a heptalene group, a fluorene group, a        spiro-bifluorene group, a benzofluorene group, a dibenzofluorene        group, a phenalene group, a phenanthrene group, an anthracene        group, a fluoranthene group, a triphenylene group, a pyrene        group, a chrysene group, a naphthacene group, a picene group, a        perylene group, a pentaphene group, an indenoanthracene group,        and an indenophenanthrene group; and    -   a naphthalene group, a heptalene group, a fluorene group, a        spiro-bifluorene group, a benzofluorene group, a dibenzofluorene        group, a phenalene group, a phenanthrene group, an anthracene        group, a fluoranthene group, a triphenylene group, a pyrene        group, a chrysene group, a naphthacene group, a picene group, a        perylene group, a pentaphene group, an indenoanthracene group,        and an indenophenanthrene group, each substituted with at least        one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,        a cyano group, a nitro group, an amidino group, a hydrazino        group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy        group, a phenyl group, a biphenyl group, a terphenyl group, and        a naphthyl group.

In embodiments, L₅₀₁ to L₅₀₃ in Formula 501 may each independently beselected from:

-   -   a phenylene group, a naphthylene group, a fluorenylene group, a        spiro-bifluorenylene group, a benzofluorenylene group, a        dibenzofluorenylene group, a phenanthrenylene group, an        anthracenylene group, a fluoranthenylene group, a        triphenylenylene group, a pyrenylene group, a chrysenylene        group, a perylenylene group, a pentaphenylene group, a        hexacenylene group, a pentacenylene group, a thiophenylene        group, a furanylene group, a carbazolylene group, an indolylene        group, an isoindolylene group, a benzofuranylene group, a        benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, and a        pyridinylene group; and    -   a phenylene group, a naphthylene group, a fluorenylene group, a        spiro-bifluorenylene group, a benzofluorenylene group, a        dibenzofluorenylene group, a phenanthrenylene group, an        anthracenylene group, a fluoranthenylene group, a        triphenylenylene group, a pyrenylene group, a chrysenylene        group, a perylenylene group, a pentaphenylene group, a        hexacenylene group, a pentacenylene group, a thiophenylene        group, a furanylene group, a carbazolylene group, an indolylene        group, an isoindolylene group, a benzofuranylene group, a        benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, and a        pyridinylene group, each substituted with at least one selected        from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazino group, a        hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group.

In embodiments, R₅₀₁ and R₅₀₂ in Formula 501 may each independently beselected from:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group; and    -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group, each substituted with at least one selected from        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl        group, a biphenyl group, a terphenyl group, a naphthyl group, a        fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl        group, a dibenzofluorenyl group, a phenanthrenyl group, an        anthracenyl group, a fluoranthenyl group, a triphenylenyl group,        a pyrenyl group, a chrysenyl group, a perylenyl group, a        pentaphenyl group, a hexacenyl group, a pentacenyl group, a        thiophenyl group, a furanyl group, a carbazolyl group, an        indolyl group, an isoindolyl group, a benzofuranyl group, a        benzothiophenyl group, a dibenzofuranyl group, a        dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, and —Si(Q₃₁)(Q₃₂)(Q₃₃),    -   wherein Q₃₁ to Q₃₃ may be selected from a C₁-C₁₀ alkyl group, a        C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a        terphenyl group, and a naphthyl group.

In embodiments, xd4 in Formula 501 may be 2, but embodiments are notlimited thereto.

For example, the organic fluorescent dopant compound may be selectedfrom compounds FD1 to FD22:

In embodiments, the organic fluorescent dopant compound may be selectedfrom the following compounds, but embodiments are not limited thereto.

The organic delayed fluorescence dopant compound refers to an organiccompound capable of emitting only delayed fluorescent light orsimultaneously emitting delayed fluorescent light and fluorescent light.

In an embodiment, the organic delayed fluorescence dopant compound mayinclude a compound represented by Formula 502:

-   -   wherein, in Formula 502,    -   A₅₀₁ to A₅₀₂ may each independently be a C₅-C₆₀ carbocyclic        group or a C₁-C₆₀ heterocyclic group,    -   L₅₀₁ to L₅₀₅ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkylene group, a        substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a        substituted or unsubstituted C₁-C₁₀ heterocycloalkenylene group,        a substituted or unsubstituted C₆-C₆₀ arylene group, a        substituted or unsubstituted C₁-C₆₀ heteroarylene group, a        substituted or unsubstituted divalent non-aromatic condensed        polycyclic group, and a substituted or unsubstituted divalent        non-aromatic condensed heteropolycyclic group,    -   a501 to a505 may each independently be an integer from 0 to 3,    -   R₅₀₃ to R₅₀₇ may each independently be selected from a        substituted or unsubstituted C₃-C₁₀ alkyl group, a substituted        or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or        unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or        unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or        unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or        unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted        C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀        arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl        group, a substituted or unsubstituted monovalent non-aromatic        condensed polycyclic group, and a substituted or unsubstituted        monovalent non-aromatic condensed heteropolycyclic group, and    -   c11 to c13 may each independently be an integer from 0 to 6.

In an embodiment, A₅₀₁ to A₅₀₃ in Formula 502 may each independently beselected from a benzene group, a naphthalene group, a heptalene group, afluorene group, a spiro-bifluorene group, a benzofluorene group, adibenzofluorene group, a phenalene group, a phenanthrene group, ananthracene group, a fluoranthene group, a triphenylene group, a pyrenegroup, a chrysene group, a naphthacene group, a picene group, a perylenegroup, a pentaphene group, an indenoanthracene group, an indenophenanthrene group, and a group represented by Formula 503:

-   -   wherein, in Formula 503,    -   A₅₀₄ to A₅₀₆ are the same as described in connection with A₅₀₁        in Formula 502,    -   L₅₀₄ to L₅₀₈ are the same as described in connection with L₅₀₁        in Formula 502,    -   a504 to a508 are the same as described in connection with a501        in Formula 502,    -   R₅₀₆ to R₅₁₀ are the same as described in connection with R₅₀₃        in Formula 502, and    -   c14 to c16 are the same as described in connection with c11 in        Formula 502.

In embodiments, L₅₀₁ to L₅₀₅ in Formula 502 are the same as describedabove.

In embodiments, R₅₀₃ to R₅₀₇ in Formula 502 may each independently beselected from:

-   -   a methyl group, an ethyl group, an n-propyl group, an iso-propyl        group, an n-butyl group, an iso-butyl group, a sec-butyl group,        a tert-butyl group, a phenyl group, a biphenyl group, a        terphenyl group, a naphthyl group, a fluorenyl group, a        spiro-bifluorenyl group, a benzofluorenyl group, a        dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl        group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl        group, a chrysenyl group, a perylenyl group, a pentaphenyl        group, a hexacenyl group, a pentacenyl group, a thiophenyl        group, a furanyl group, a carbazolyl group, an indolyl group, an        isoindolyl group, a benzofuranyl group, a benzothiophenyl group,        a dibenzofuranyl group, a dibenzothiophenyl group, a        benzocarbazolyl group, a dibenzocarbazolyl group, a        dibenzosilolyl group, and a pyridinyl group; and    -   a methyl group, an ethyl group, an n-propyl group, an iso-propyl        group, an n-butyl group, an isobutyl group, a sec-butyl group, a        tert-butyl group, a phenyl group, a biphenyl group, a terphenyl        group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl        group, a benzofluorenyl group, a dibenzofluorenyl group, a        phenanthrenyl group, an anthracenyl group, a fluoranthenyl        group, a triphenylenyl group, a pyrenyl group, a chrysenyl        group, a perylenyl group, a pentaphenyl group, a hexacenyl        group, a pentacenyl group, a thiophenyl group, a furanyl group,        a carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl        group, each substituted with at least one selected from        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl        group, a biphenyl group, a terphenyl group, a naphthyl group, a        fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl        group, a dibenzofluorenyl group, a phenanthrenyl group, an        anthracenyl group, a fluoranthenyl group, a triphenylenyl group,        a pyrenyl group, a chrysenyl group, a perylenyl group, a        pentaphenyl group, a hexacenyl group, a pentacenyl group, a        thiophenyl group, a furanyl group, a carbazolyl group, an        indolyl group, an isoindolyl group, a benzofuranyl group, a        benzothiophenyl group, a dibenzofuranyl group, a        dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, and —Si(Q₃₁)(Q₃₂)(Q₃₃),    -   wherein Q₃₁ to Q₃₃ may be selected from a C₁-C₁₀ alkyl group, a        C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a        terphenyl group, and a naphthyl group.

In an embodiment, c11 to c13 in Formula 502 may be 0 or 1, butembodiments are not limited thereto.

For example, the delayed fluorescence dopant compound may be selectedfrom Compounds FD23 to FD25 below:

The organometallic phosphorescent dopant compound refers to an organiccompound that may emit phosphorescent light.

In an embodiment, the organometallic phosphorescent dopant compound maybe represented by Formula 401:

In Formulae 401 and 402,

-   -   M may be selected from iridium (Ir), platinum (Pt), palladium        (Pd), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf),        europium (Eu), terbium (Tb), rhodium (Rh), and thulium (Tm),    -   L₄₀₁ may be a ligand represented by Formula 402, and xc1 may be        1, 2, or 3, wherein when xc1 is two or more, two or more L₄₀₁(s)        may be identical to or different from each other,    -   L₄₀₂ may be an organic ligand, and xc2 may be an integer from 0        to 4, wherein when xc2 may be two or more, two or more L₄₀₂(s)        may be identical to or different from each other,    -   X₄₀₁ to X₄₀₄ may each independently be nitrogen or carbon,    -   X₄₀₁ and X₄₀₃ may be linked via a single bond or a double bond,        and X₄₀₂ and X₄₀₄ may be linked via a single bond or a double        bond,    -   A₄₀₁ and A₄₀₂ may each independently be a C₅-C₆₀ carbocyclic        group or a C₁-C₆₀ heterocyclic group,    -   X₄₀₅ may be a single bond, *—O—*′, *—S—*′, *—C(═O)—*′,        *—N(Q₄₁₁)-*′, *—C(Q₄₁₁)(Q₄₁₂)-*′, *—C(Q₄₁₁)=C(Q₄₁₂)-*′,        *—C(Q₄₁₁)=*′, or *═C(Q₄₁₁)=*′, wherein Q₄₁₁ and Q₄₁₂ may be        hydrogen, deuterium, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy        group, a phenyl group, a biphenyl group, a terphenyl group, or a        naphthyl group,    -   X₄₀₆ may be a single bond, O, or S,    -   R₄₀₁ and R₄₀₂ may each independently be selected from hydrogen,        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a substituted or unsubstituted C₁-C₂₀ alkyl group, a        substituted or unsubstituted C₁-C₂₀ alkoxy group, a substituted        or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or        unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or        unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or        unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or        unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted        C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀        arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl        group, a substituted or unsubstituted monovalent non-aromatic        condensed polycyclic group, and a substituted or unsubstituted        monovalent non-aromatic condensed heteropolycyclic group,        —Si(Q₄₀₁)(Q₄₀₂)(Q₄₀₃), —N(Q₄₀₁)(Q₄₀₂), —B(Q₄₀₁)(Q₄₀₂),        —C(═O)(Q₄₀₁), —S(═O)₂(Q₄₀₁), and —P(═O)(Q₄₀₁)(Q₄₀₂), and Q₄₀₁ to        Q₄₀₃ may each independently be selected from a C₁-C₁₀ alkyl        group, a C₁-C₁₀ alkoxy group, a C₆-C₂₀ aryl group, and a C₁-C₂₀        heteroaryl group,    -   xc11 and xc12 may each independently be an integer from 0 to 3,        and    -   * and *′ in Formula 402 each indicate a binding site to M in        Formula 401.

In an embodiment, A₄₀₁ and A₄₀₂ in Formula 402 may each independently beselected from a benzene group, a naphthalene group, a fluorene group, aspiro-bifluorene group, an indene group, a pyrrole group, a thiophenegroup, a furan group, an imidazole group, a pyrazole group, a thiazolegroup, an isothiazole group, an oxazole group, an isoxazole group, apyridine group, a pyrazine group, a pyrimidine group, a pyridazinegroup, a quinoline group, an isoquinoline group, a benzoquinoline group,a quinoxaline group, a quinazoline group, a carbazole group, abenzimidazole group, a benzofuran group, a benzothiophene group, anisobenzothiophene group, a benzoxazole group, an isobenzoxazole group, atriazole group, a tetrazole group, an oxadiazole group, a triazinegroup, a dibenzofuran group, and a dibenzothiophene group.

In embodiments, in Formula 402, i) X₄₀₁ may be nitrogen and X₄₀₂ may becarbon, or ii) X₄₀₁ and X₄₀₂ may each be nitrogen at the same time.

In embodiments, R₄₀₁ and R₄₀₂ in Formula 402 may each independently beselected from:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazino group, a        hydrazono group, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy        group;    -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted        with at least one selected from deuterium, —F, —Cl, —Br, —I, a        hydroxyl group, a cyano group, a nitro group, an amidino group,        a hydrazino group, a hydrazono group, a phenyl group, a naphthyl        group, a cyclopentyl group, a cyclohexyl group, an adamantanyl        group, a norbornanyl group, and a norbornenyl group;    -   a cyclopentyl group, a cyclohexyl group, an adamantanyl group, a        norbornanyl group, a norbornenyl group, a phenyl group, a        biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl        group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl        group, a pyridazinyl group, a triazinyl group, a quinolinyl        group, an isoquinolinyl group, a quinoxalinyl group, a        quinazolinyl group, a carbazolyl group, a dibenzofuranyl group,        and a dibenzothiophenyl group;    -   a cyclopentyl group, a cyclohexyl group, an adamantanyl group, a        norbornanyl group, a norbornenyl group a phenyl group, a        biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl        group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl        group, a pyridazinyl group, a triazinyl group, a quinolinyl        group, an isoquinolinyl group, a quinoxalinyl group, a        quinazolinyl group, a carbazolyl group, a dibenzofuranyl group,        and a dibenzothiophenyl group, each substituted with at least        one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,        a cyano group, a nitro group, an amidino group, a hydrazino        group, a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy        group, a cyclopentyl group, a cyclohexyl group, an adamantanyl        group, a norbornanyl group, a norbornenyl group, a phenyl group,        a biphenyl group, a terphenyl group, a naphthyl group, a        fluorenyl group, a pyridinyl group, a pyrazinyl group, a        pyrimidinyl group, a pyridazinyl group, a triazinyl group, a        quinolinyl group, an isoquinolinyl group, a quinoxalinyl group,        a quinazolinyl group, a carbazolyl group, a dibenzofuranyl        group, and a dibenzothiophenyl group; and    -   —Si(Q₄₀₁)(Q₄₀₂)(Q₄₀₃), —N(Q₄₀₁)(Q₄₀₂), —B(Q₄₀₁)(Q₄₀₂),        —C(═O)(Q₄₀₁), —S(═O)₂(Q₄₀₁), and —P(═O)(Q₄₀₁)(Q₄₀₂),    -   wherein Q₄₀₁ to Q₄₀₃ may each independently be selected from a        C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a        biphenyl group, and a naphthyl group, but embodiments are not        limited thereto.

In embodiments, when xc1 in Formula 401 is 2 or more, two A₄₀₁(s) in twoor more L₄₀₁(s) may optionally be linked to each other via X₄₀₇, whichis a linking group, two A₄₀₂(s) may optionally be linked to each othervia X₄₀₈, which is a linking group (see Compounds PD1 to PD4 and PD7below). X₄₀₇ and X₄₀₈ may each independently be a single bond, *—O—*′,*—S—*′, *—C(═O)—*′, *—N(Q₄₁₃)-*′, *—C(Q₄₁₃)(Q₄₁₄)-*′, or*—C(Q₄₁₃)=C(Q₄₁₄)-*′ (where Q₄₁₃ and Q₄₁₄ may each independently behydrogen, deuterium, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, aphenyl group, a biphenyl group, a terphenyl group, or a naphthyl group),but embodiments are not limited thereto.

L₄₀₂ in Formula 401 may be a monovalent, divalent, or trivalent organicligand. For example, L₄₀₂ may be selected from halogen, diketone (forexample, acetylacetonate), carboxylic acid (for example, picolinate),—C(═O), isonitrile, —CN, and phosphorus (for example, phosphine, orphosphite), but embodiments are not limited thereto.

In embodiments, the organometallic phosphorescent dopant may be selectedfrom, for example, Compounds PD1 to PD25 below, but embodiments are notlimited thereto:

The volume of the first material may be greater than or equal to thevolume of the second material. In an embodiment, the volume ratio of thefirst material to the second material may be in a range of about 99:1 toabout 50:50, but embodiments are not limited thereto. Within theabove-described range, the second material may form an energy levelwhich is selective with respect to the first material and thus, may actas a sensitizer sufficiently.

The volume of the third material in the emission layer may be in a rangeof about 1% to about 15%, but embodiments are not limited thereto.Within the above-mentioned range, the third material may sufficientlyact as a light-emitting dopant.

A thickness of the emission layer may be in a range of about 0.1 nm toabout 100 nm. For example, the thickness of the emission layer may be ina range of about 15 nm to about 50 nm. For example, when the emissionlayer emits blue light, a thickness of the blue emission layer may be ina range of about 15 nm to about 20 nm. For example, when the emissionlayer emits green light, a thickness of the green emission layer may bein a range of about 20 nm to about 40 nm. For example, when the emissionlayer emits red light, a thickness of the red emission layer may be in arange of about 40 nm to about 50 nm. When the thickness of the emissionlayer is within these ranges, the light-emitting device 1 may haveexcellent light-emission characteristics without a substantial increasein driving voltage.

[Electron Transport Region in Middle Layer 150]

The electron transport region may have i) a single-layered structureincluding a single layer including a single material, ii) asingle-layered structure including a single layer including differentmaterials, or iii) a multi-layered structure having multiple layersincluding different materials.

The electron transport region may include a hole blocking layer, anelectron transport layer, an electron injection layer, or anycombination thereof, but embodiments are not limited thereto.

[Electron Injection Layer in Electron Transport Region]

The light-emitting device may include an electron injection layer incontact (e.g., direct contact) with the second electrode.

The electron injection layer may include a sixth material, and the sixthmaterial may include an alkali metal halide, an alkaline earth metalhalide, a lanthanide metal halide, or any combination thereof.

In an embodiment, the electron injection layer may consist of a sixthmaterial. For example, the electron injection layer may not include anymaterial other than the sixth material.

In embodiments, the electron injection layer may further include aseventh material, and the sixth material and the seventh material may bedifferent from each other. The seventh material may include an alkalimetal, an alkaline earth metal, a lanthanide metal, or any combinationthereof.

In an embodiment, the sixth material may be a compound having a wideband gap of about 7 eV or more. Accordingly, the sixth material may notsubstantially absorb light.

In an embodiment, the seventh material may be a compound having a lowwork function of about 2.6 eV or less.

In an embodiment, the sixth material may be represented by Formula X,and the seventh material may be represented by Formula Y:A_(n)B_(m)  <Formula X>C  <Formula Y>

In Formulae X and Y,

-   -   A and C may each independently include an alkali metal, an        alkaline earth metal, a lanthanide metal, or any combination        thereof,    -   B may be a halogen,    -   n and m may each independently be an integer of 1 or more that        makes the sixth material neutral, and    -   A and C may be different from each other.

When A and C are different from each other, the seventh material maycomplement light absorption according to a narrow band gap of the sixthmaterial.

For example, in Formulae X and Y, A may include Li, Na, K, Rb, Cs, orany combination thereof, B may include F, Cl, Br, I, or any combinationthereof, each of n and m is 1, and C may include La, Ce, Pr, Nd, Pm, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or any combination thereof.

In an embodiment, the sixth material may include NaI, KI, RbI, CsI,NaCl, KCl, RbCl, CsCl, NaF, KF, RbF, CsF, or any combination thereof,and the seventh material may include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, Lu, or any combination thereof.

In the electron injection layer, the volume of the sixth material may begreater than or equal to the volume of the seventh material. In anembodiment, in the electron injection layer, the volume percentage ofthe seventh material may be greater than 0% and less than or equal to50%. In an embodiment, in the electron injection layer, the volumepercentage of the seventh material may be in a range of about 5% toabout 10%, but embodiments are not limited thereto. When the volume ofthe seventh material is within the range above, the seventh material maybe sufficient to complement light absorption according to a narrow bandgap of the sixth material.

A thickness of the electron injection layer may be in a range of about0.1 nm to about 5 nm. When the thickness of the electron injection layeris within the range above, satisfactory electron injectioncharacteristics may be obtained without a substantial increase indriving voltage.

[Electron Transport Layer in Electron Transport Region]

The light-emitting device 1 may include an electron transport layercontacting (e.g., directly contacting) the emission layer.

The electron transport layer may include a tenth material and aneleventh material, and the tenth material and the eleventh material maybe different from each other. The tenth material may include at leastone electron transport organic compound, and the eleventh material mayinclude an alkali metal halide, an alkaline earth metal halide, alanthanide metal halide, or any combination thereof.

The term “electron transport organic compound” as used herein refers toa metal-free compound including at least one π electron-deficientnitrogen-containing ring.

The “π electron-depleted nitrogen-containing ring” indicates a C₁-C₆₀heterocyclic group having at least one *—N═*′ moiety as a ring-formingmoiety.

For example, the “π electron-depleted nitrogen-containing ring” may bei) a 5-membered to 7-membered heteromonocyclic group having at least one*—N═*′ moiety, ii) a heteropolycyclic group in which two or more5-membered to 7-membered heteromonocyclic groups each having at leastone *—N═*′ moiety are condensed with each other, or iii) aheteropolycyclic group in which at least one of 5-membered to 7-memberedheteromonocyclic groups, each having at least one *—N═*′ moiety, iscondensed with at least one C₅-C₆₀ carbocyclic group.

Examples of the π electron-deficient nitrogen-containing ring include animidazole ring, a pyrazole ring, a thiazole ring, an isothiazole ring,an oxazole ring, an isoxazole ring, a pyridine ring, a pyrazine ring, apyrimidine ring, a pyridazine ring, an indazole ring, a purine ring, aquinoline ring, an isoquinoline ring, a benzoquinoline ring, aphthalazine ring, a naphthyridine ring, a quinoxaline ring, aquinazoline ring, a cinnoline ring, a phenanthridine ring, an acridinering, a phenanthroline ring, a phenazine ring, a benzimidazole ring, anisobenzothiazole ring, a benzoxazole ring, an isobenzoxazole ring, atriazole ring, a tetrazole ring, an oxadiazole ring, a triazine ring, athiadiazole ring, an imidazopyridine ring, an imidazopyrimidine ring,and an azacarbazole ring, but are not limited thereto.

The term “electron transport organic compound” as used herein mayinclude a compound represented by Formula 601:[Ar₆₀₁]_(xe11)-[(L₆₀₁)_(xe1)-R₆₀₁]_(xe21)  <Formula 601>

In Formula 601,

-   -   Ar₆₀₁ may be a substituted or unsubstituted C₅-C₆₀ carbocyclic        group or a substituted or unsubstituted C₁-C₆₀ heterocyclic        group,    -   xe11 may be 1, 2, or 3,    -   L₆₀₁ may be selected from a substituted or unsubstituted C₃-C₁₀        cycloalkylene group, a substituted or unsubstituted C₁-C₁₀        heterocycloalkylene group, a substituted or unsubstituted C₃-C₁₀        cycloalkenylene group, a substituted or unsubstituted C₁-C₁₀        heterocycloalkenylene group, a substituted or unsubstituted        C₆-C₆₀ arylene group, a substituted or unsubstituted C₁-C₆₀        heteroarylene group, a substituted or unsubstituted divalent        non-aromatic condensed polycyclic group, and a substituted or        unsubstituted divalent non-aromatic condensed heteropolycyclic        group,    -   xe1 may be an integer from 0 to 5,    -   R₆₀₁ may be selected from a substituted or unsubstituted C₃-C₁₀        cycloalkyl group, a substituted or unsubstituted C₁-C₁₀        heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀        cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀        heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀        aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group,        a substituted or unsubstituted C₆-C₆₀ arylthio group, a        substituted or unsubstituted C₁-C₆₀ heteroaryl group, a        substituted or unsubstituted monovalent non-aromatic condensed        polycyclic group, a substituted or unsubstituted monovalent        non-aromatic condensed heteropolycyclic group,        —Si(Q₆₀₁)(Q₆₀₂)(Q₆₀₃), —C(═O)(Q₆₀₁), —S(═O)₂(Q₆₀₁), and        —P(═O)(Q₆₀₁)(Q₆₀₂),    -   Q₆₀₁ to Q₆₀₃ may each independently be a C₁-C₁₀ alkyl group, a        C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a        terphenyl group, or a naphthyl group, and    -   xe21 may be an integer from 1 to 5.

In an embodiment, at least one of Ar₆₀₁(s) in the number of xe11 andR₆₀₁(s) in the number of xe21 may include the π electron-depletednitrogen-containing ring.

In an embodiment, Ar₆₀₁ in Formula 601 may be selected from:

-   -   a benzene group, a naphthalene group, a fluorene group, a        spiro-bifluorene group, a benzofluorene group, a dibenzofluorene        group, a phenalene group, a phenanthrene group, an anthracene        group, a fluoranthene group, a triphenylene group, a pyrene        group, a chrysene group, a naphthacene group, a picene group, a        perylene group, a pentaphene group, an indenoanthracene group, a        dibenzofuran group, a dibenzothiophene group, a carbazole group,        an imidazole group, a pyrazole group, a thiazole group, an        isothiazole group, an oxazole group, an isoxazole group, a        pyridine group, a pyrazine group, a pyrimidine group, a        pyridazine group, an indazole group, a purine group, a quinoline        group, an isoquinoline group, a benzoquinoline group, a        phthalazine group, a naphthyridine group, a quinoxaline group, a        quinazoline group, a cinnoline group, a phenanthridine group, an        acridine group, a phenanthroline group, a phenazine group, a        benzimidazole group, an isobenzothiazole group, a benzoxazole        group, an isobenzoxazole group, a triazole group, a tetrazole        group, an oxadiazole group, a triazine group, a thiadiazole        group, an imidazopyridine group, an imidazopyrimidine group, and        an azacarbazole group; and    -   a benzene group, a naphthalene group, a fluorene group, a        spiro-bifluorene group, a benzofluorene group, a dibenzofluorene        group, a phenalene group, a phenanthrene group, an anthracene        group, a fluoranthene group, a triphenylene group, a pyrene        group, a chrysene group, a naphthacene group, a picene group, a        perylene group, a pentaphene group, an indenoanthracene group, a        dibenzofuran group, a dibenzothiophene group, a carbazole group,        an imidazole group, a pyrazole group, a thiazole group, an        isothiazole group, an oxazole group, an isoxazole group, a        pyridine group, a pyrazine group, a pyrimidine group, a        pyridazine group, an indazole group, a purine group, a quinoline        group, an isoquinoline group, a benzoquinoline group, a        phthalazine group, a naphthyridine group, a quinoxaline group, a        quinazoline group, a cinnoline group, a phenanthridine group, an        acridine group, a phenanthroline group, a phenazine group, a        benzimidazole group, an isobenzothiazole group, a benzoxazole        group, an isobenzoxazole group, a triazole group, a tetrazole        group, an oxadiazole group, a triazine group, a thiadiazole        group, an imidazopyridine group, an imidazopyrimidine group, and        an azacarbazole group, each substituted with at least one        selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a        cyano group, a nitro group, an amidino group, a hydrazino group,        a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group,        a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, —Si(Q₃₁)(Q₃₂)(Q₃₃), —S(═O)₂(Q₃₁), and —P(═O)(Q₃₁)(Q₃₂),    -   wherein Q₃₁ to Q₃₃ may each independently be selected from a        C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a        biphenyl group, a terphenyl group, and a naphthyl group.

When xe11 in Formula 601 is 2 or more, two or more Ar₆₀₁(s) may belinked to each other via a single bond.

In embodiments, Ar₆₀₁ in Formula 601 may be an anthracene group.

In embodiments, a compound represented by Formula 601 may be representedby Formula 601-1 below:

-   -   wherein, in Formula 601-1,    -   X₆₁₄ may be N or C(R₆₁₄), X₆₁₅ may be N or C(R₆₁₅), X₆₁₆ may be        N or C(R₆₁₆), and at least one of X₆₁₄ to X₆₁₆ may be N,    -   L₆₁₁ to L₆₁₃ may each independently be the same as described in        connection with L₆₀₁,    -   xe611 to xe613 may each independently be the same as described        in connection with xe1,    -   R₆₁₁ to R₆₁₃ may each independently be the same as described in        connection with R₆₀₁, and    -   R₆₁₄ to R₆₁₆ may each independently be selected from hydrogen,        deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazino group, a hydrazono        group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl        group, a biphenyl group, a terphenyl group, and a naphthyl        group.

In an embodiment, L₆₀₁ and L₆₁₁ to L₆₁₃ in Formulae 601 and 601-1 mayeach independently be selected from:

-   -   a phenylene group, a naphthylene group, a fluorenylene group, a        spiro-bifluorenylene group, a benzofluorenylene group, a        dibenzofluorenylene group, a phenanthrenylene group, an        anthracenylene group, a fluoranthenylene group, a        triphenylenylene group, a pyrenylene group, a chrysenylene        group, a perylenylene group, a pentaphenylene group, a        hexacenylene group, a pentacenylene group, a thiophenylene        group, a furanylene group, a carbazolylene group, an indolylene        group, an isoindolylene group, a benzofuranylene group, a        benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, a        pyridinylene group, an imidazolylene group, a pyrazolylene        group, a thiazolylene group, an isothiazolylene group, an        oxazolylene group, an isoxazolylene group, a thiadiazolylene        group, an oxadiazolylene group, a pyrazinylene group, a        pyrimidinylene group, a pyridazinylene group, a triazinylene        group, a quinolinylene group, an isoquinolinylene group, a        benzoquinolinylene group, a phthalazinylene group, a        naphthyridinylene group, a quinoxalinylene group, a        quinazolinylene group, a cinnolinylene group, a        phenanthridinylene group, an acridinylene group, a        phenanthrolinylene group, a phenazinylene group, a        benzimidazolylene group, an isobenzothiazolylene group, a        benzoxazolylene group, an isobenzoxazolylene group, a        triazolylene group, a tetrazolylene group, an        imidazopyridinylene group, an imidazopyrimidinylene group, and        an azacarbazolylene group; and    -   a phenylene group, a naphthylene group, a fluorenylene group, a        spiro-bifluorenylene group, a benzofluorenylene group, a        dibenzofluorenylene group, a phenanthrenylene group, an        anthracenylene group, a fluoranthenylene group, a        triphenylenylene group, a pyrenylene group, a chrysenylene        group, a perylenylene group, a pentaphenylene group, a        hexacenylene group, a pentacenylene group, a thiophenylene        group, a furanylene group, a carbazolylene group, an indolylene        group, an isoindolylene group, a benzofuranylene group, a        benzothiophenylene group, a dibenzofuranylene group, a        dibenzothiophenylene group, a benzocarbazolylene group, a        dibenzocarbazolylene group, a dibenzosilolylene group, a        pyridinylene group, an imidazolylene group, a pyrazolylene        group, a thiazolylene group, an isothiazolylene group, an        oxazolylene group, an isoxazolylene group, a thiadiazolylene        group, an oxadiazolylene group, a pyrazinylene group, a        pyrimidinylene group, a pyridazinylene group, a triazinylene        group, a quinolinylene group, an isoquinolinylene group, a        benzoquinolinylene group, a phthalazinylene group, a        naphthyridinylene group, a quinoxalinylene group, a        quinazolinylene group, a cinnolinylene group, a        phenanthridinylene group, an acridinylene group, a        phenanthrolinylene group, a phenazinylene group, a        benzimidazolylene group, an isobenzothiazolylene group, a        benzoxazolylene group, an isobenzoxazolylene group, a        triazolylene group, a tetrazolylene group, an        imidazopyridinylene group, an imidazopyrimidinylene group, and        an azacarbazolylene group, each substituted with at least one        selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a        cyano group, a nitro group, an amidino group, a hydrazino group,        a hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group,        a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, an imidazolyl group, a pyrazolyl group, a thiazolyl        group, an isothiazolyl group, an oxazolyl group, an isoxazolyl        group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl        group, a pyrimidinyl group, a pyridazinyl group, a triazinyl        group, a quinolinyl group, an isoquinolinyl group, a        benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl        group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl        group, a phenanthridinyl group, an acridinyl group, a        phenanthrolinyl group, a phenazinyl group, a benzimidazolyl        group, an isobenzothiazolyl group, a benzoxazolyl group, an        isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an        imidazopyridinyl group, an imidazopyrimidinyl group, and an        azacarbazolyl group,    -   but embodiments are not limited thereto.

In embodiments, xe1 and xe611 to xe613 in Formulae 601 and 601-1 mayeach independently be 0, 1, or 2.

In embodiments, R₆₀₁ and R₆₁₁ to R₆₁₃ in Formulae 601 and 601-1 may eachindependently be selected from:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, an imidazolyl group, a pyrazolyl group, a thiazolyl        group, an isothiazolyl group, an oxazolyl group, an isoxazolyl        group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl        group, a pyrimidinyl group, a pyridazinyl group, a triazinyl        group, a quinolinyl group, an isoquinolinyl group, a        benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl        group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl        group, a phenanthridinyl group, an acridinyl group, a        phenanthrolinyl group, a phenazinyl group, a benzimidazolyl        group, an isobenzothiazolyl group, a benzoxazolyl group, an        isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an        imidazopyridinyl group, an imidazopyrimidinyl group, and an        azacarbazolyl group;    -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, an imidazolyl group, a pyrazolyl group, a thiazolyl        group, an isothiazolyl group, an oxazolyl group, an isoxazolyl        group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl        group, a pyrimidinyl group, a pyridazinyl group, a triazinyl        group, a quinolinyl group, an isoquinolinyl group, a        benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl        group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl        group, a phenanthridinyl group, an acridinyl group, a        phenanthrolinyl group, a phenazinyl group, a benzimidazolyl        group, an isobenzothiazolyl group, a benzoxazolyl group, an        isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an        imidazopyridinyl group, an imidazopyrimidinyl group, and an        azacarbazolyl group, each substituted with at least one selected        from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazino group, a        hydrazono group, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a        phenyl group, a biphenyl group, a terphenyl group, a naphthyl        group, a fluorenyl group, a spiro-bifluorenyl group, a        benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl        group, an anthracenyl group, a fluoranthenyl group, a        triphenylenyl group, a pyrenyl group, a chrysenyl group, a        perylenyl group, a pentaphenyl group, a hexacenyl group, a        pentacenyl group, a thiophenyl group, a furanyl group, a        carbazolyl group, an indolyl group, an isoindolyl group, a        benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl        group, a dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl        group, an imidazolyl group, a pyrazolyl group, a thiazolyl        group, an isothiazolyl group, an oxazolyl group, an isoxazolyl        group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl        group, a pyrimidinyl group, a pyridazinyl group, a triazinyl        group, a quinolinyl group, an isoquinolinyl group, a        benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl        group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl        group, a phenanthridinyl group, an acridinyl group, a        phenanthrolinyl group, a phenazinyl group, a benzimidazolyl        group, an isobenzothiazolyl group, a benzoxazolyl group, an        isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an        imidazopyridinyl group, an imidazopyrimidinyl group, and an        azacarbazolyl group; and    -   —S(═O)₂(Q₆₀₁) and —P(═O)(Q₆₀₁)(Q₆₀₂),    -   wherein Q₆₀₁ and Q₆₀₂ are the same as described above.

The electron transport region may include at least one compound selectedfrom Compounds ET1 to ET36, but embodiments are not limited thereto:

In embodiments, the electron transport region may include at least oneselected from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),4,7-dphenyl-1,10-phenanthroline (Bphen), Alq₃, BAlq,3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole(TAZ), and NTAZ:

In the electron transport layer, a volume of the tenth material may begreater than or equal to a volume of the eleventh material. In anembodiment, in the electron transport layer, a volume ratio of the tenthmaterial to the eleventh material may be in a range of about 99:1 toabout 50:50.

A thickness of the electron transport layer may be in a range of about0.1 nm to about 10 nm. When the thickness of the electron transportlayer is within the range above, satisfactory electron transportcharacteristics may be obtained without a substantial increase indriving voltage.

[Metal-Containing Material in Electron Transport Region]

The electron transport region may further include, in addition to thematerials described above, a metal-containing material.

The metal-containing material may include at least one selected from analkali metal complex and an alkaline earth-metal complex.

A ligand coordinated with the metal ion of the alkali metal complex orthe alkaline earth-metal complex may be selected from a hydroxyquinoline, a hydroxy isoquinoline, a hydroxy benzoquinoline, a hydroxyacridine, a hydroxy phenanthridine, a hydroxy phenyloxazole, a hydroxyphenylthiazole, a hydroxy diphenyloxadiazole, a hydroxydiphenylthiadiazole, a hydroxy phenylpyridine, a hydroxyphenylbenzimidazole, a hydroxy phenylbenzothiazole, a bipyridine, aphenanthroline, and a cyclopentadiene, but embodiments are not limitedthereto.

For example, the metal-containing material may include a Li complex. TheLi complex may include, for example, Compound ET-D1 (lithium quinolate,LiQ) or ET-D2:

[Second Electrode 190]

The second electrode 190 may be located on the middle layer 150 havingsuch a structure. The second electrode 190 may be a cathode which is anelectron injection electrode, and in this regard, a material for formingthe second electrode 190 may be selected from a metal, an alloy, anelectrically conductive compound, and a combination thereof, which havea relatively low work function.

The second electrode 190 may include at least one selected from lithium(Li), silver (Ag), magnesium (Mg), aluminum (Al), aluminum-lithium(Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver(Mg—Ag), ITO, and IZO, but embodiments are not limited thereto. Thesecond electrode 190 may be a transmissive electrode, asemi-transmissive electrode, or a reflective electrode.

The second electrode 190 may have a single-layered structure or amulti-layered structure including two or more layers.

A thickness of the second electrode 190 may be in a range of about 5 nmto about 20 nm. Within this range, light absorption at the secondelectrode may be minimized.

[Description of FIGS. 2 to 4 ]

The light-emitting device may further include a first capping layerand/or a second capping layer. In an embodiment, a first capping layer210, an anode 110, an interlayer 150, and a cathode 190 may besequentially stacked in this stated order (see FIG. 2 ), or the anode110, the interlayer 150, the cathode 190, and a second capping layer 220may be sequentially stacked in this stated order (see FIG. 3 ), and thefirst capping layer 210, the anode 110, the interlayer 150, the cathode190, and the second capping layer 220 may be sequentially stacked inthis stated order (see FIG. 4 ).

Light generated in an emission layer of an interlayer of alight-emitting device may be emitted through an anode, which is asemi-transmissive electrode or transmissive electrode, and a firstcapping layer, or light generated in the emission layer of theinterlayer of the light-emitting device may be emitted through acathode, which is a semi-transmissive electrode or transmissiveelectrode, and a second capping layer.

The first capping layer and the second capping layer may increaseexternal luminescence efficiency according to the principle ofconstructive interference.

The first capping layer and the second capping layer may eachindependently be an organic capping layer including an organic material,an inorganic capping layer including an inorganic material, or acomposite capping layer including an organic material and an inorganicmaterial.

At least one selected from the first capping layer and the secondcapping layer may each independently include at least one materialselected from carbocyclic compounds, heterocyclic compounds, amine-basedcompounds, porphyrine derivatives, phthalocyanine derivatives, anaphthalocyanine derivatives, alkali metal complexes, and alkalineearth-based complexes. The carbocyclic compound, the heterocycliccompound, and the amine-based compound may be optionally substitutedwith a substituent containing at least one element selected from O, N,S, Se, Si, F, Cl, Br, and I. In an embodiment, at least one of the firstcapping layer and the second capping layer may each independentlyinclude an amine-based compound.

In embodiments, at least one of the first capping layer and the secondcapping layer may each independently include a compound represented byFormula 201 or a compound represented by Formula 202.

In embodiments, at least one of the first capping layer and the secondcapping layer may each independently include a compound selected fromCompounds HT28 to HT33 and Compounds CP1 to CP5, but embodiments are notlimited thereto.

[Tandem Light-Emitting Device]

FIG. 5 is a schematic cross-sectional view of a light-emitting device 5according to an embodiment.

Referring to FIG. 5 , the light-emitting device 5 according to anembodiment may include: a first electrode 510; a second electrode 590facing the first electrode; n light-emitting units ELU1 through ELU(n)located between the first electrode and the second electrode; and n−1charge generating units CGU(n−1)(s) located between neighboringlight-emitting units, wherein n is a natural number of 2 or more, andeach of the light-emitting units may include an emission layer.

The n light-emitting units may emit different color of light oridentical color of light.

In an embodiment, the n light-emitting units may all emit blue light,but embodiments are not limited thereto.

In an embodiment, the charge generating units may each include an n-typecharge generating layer.

The n-type charge generating layer may include a twelfth material and athirteenth material.

The twelfth material may include an alkali metal, an alkaline earthmetal, a lanthanide metal, a transition metal, a post-transition metal,or any combination thereof.

The thirteenth material may include one or more electron transportorganic compounds.

The volume ratio of the thirteenth material to the twelfth material maybe in a range of about 99:1 to about 80:20.

A thickness of the n-type charge-generating layer may be in a range ofabout 0.1 nm to about 20 nm.

In an embodiment, each of the charge generating units may furtherinclude a p-type charge generating layer.

The p-type charge generating layer may include a fourteenth material anda fifteenth material.

The fourteenth material may include a hole transport organic compound,an inorganic insulator compound, or any combination thereof.

The fifteenth material may include one or more inorganic semiconductorcompounds.

For example, the fourteenth material may include a hole transportorganic compound, and the volume ratio of the fourteenth material to thefifteenth material may be in a range of about 99:1 to about 80:20.

In embodiments, the fourteenth material may include an inorganicinsulator compound, and the volume ratio of the fourteenth material tothe fifteenth material may be in a range of about 99:1 to about 50:50.

A thickness of the p-type charge generating layer may be in a range ofabout 0.1 nm to about 20 nm.

In an embodiment, the first electrode may be an anode, the secondelectrode may be a cathode, an n^(th) light-emitting unit may be locatedbetween the first electrode and the second electrode, an n−1^(th)light-emitting unit located between the first electrode and the n^(th)light-emitting unit, an n−1^(th) charge generating unit located betweenthe n^(th) light-emitting unit and the n−1^(th) light-emitting unit, then^(th) light-emitting unit may include an n^(th) emission layer, then−1^(th) light-emitting unit may include an n−1^(th) emission layer, ann−1^(th) hole transport region may be further located between the firstelectrode and the n−1^(th) emission layer, an n−1^(th) electrontransport region may be further located between the n^(th) emissionlayer and the n−1^(th) charge generating unit, an n^(th) hole transportregion may be further located between the n−1^(th) charge generatingunit and the n^(th) emission layer, and an n^(th) electron transportregion may be further located between the n^(th) emission layer and thesecond electrode.

The hole transport regions may each include a hole injection layer, ahole transport layer, an electron blocking layer, or any combinationthereof, and the electron transport regions may each include a holeblocking layer, an electron transport layer, an electron injectionlayer, or any combination thereof.

Since each component has the same or similar function as thecorresponding component of the embodiment according to FIG. 1 describedabove, a detailed description thereof will be omitted.

[Apparatus]

The light-emitting device may be included in various apparatuses. Forexample, a light-emitting apparatus, an authentication apparatus, or anelectronic apparatus, which includes the light-emitting device, may beprovided.

[Light-Emitting Apparatus]

In the light-emitting apparatus, a color filter may be located on atleast one traveling direction of light emitted from the light-emittingdevice. For example, the light emitted from the light-emitting devicemay be blue light, but embodiments are not limited thereto.

A first substrate of the light-emitting apparatus may include subpixelareas, and the color filter may include color filter areas respectivelycorresponding to the subpixel areas. A pixel-defining film may be formedbetween subpixel areas to define each of the subpixel areas. The colorfilter may include light-blocking patterns between the color filterareas.

The color filter areas may include a first color filter area emittingfirst color light, a second color filter area emitting second colorlight, and a third color filter area emitting third color light, and thefirst color light, the second color light, and the third color light mayhave different maximum emission wavelengths from one another. Forexample, the first color light may be red light, the second color lightmay be green light, and the third color light may be blue light, butembodiments are not limited thereto.

For example, the color filter areas may each include a quantum dot, oronly some of the color filter areas may include a quantum dot.

In an embodiment, the first color filter area may include a red quantumdot, the second color filter area may include a green quantum dot, andthe third color filter area may not include a quantum dot. In thisregard, the light-emitting device may emit first light, the first colorfilter area may absorb the first light to emit first first-color light,the second color filter area may absorb the first light to emit secondfirst-color light, and the third color filter area may allow the firstlight to pass therethrough. In this regard, the first first-color light,the second first-color light, and the first light may have differentmaximum luminescence wavelengths from one another. The first light maybe blue light, the first first-color light may be red light, the secondfirst-color light may be green light, but embodiments are not limitedthereto.

In an embodiment, the first color filter area may include a red quantumdot, the second color filter area may include a green quantum dot, andthe third color filter area may include a blue quantum dot. Thelight-emitting device may emit first light, the first color filter areamay absorb the first light to emit first first-color light, the secondcolor filter area may absorb the first light to emit second first-colorlight, and the third color filter area may absorb the first light toemit third first-color light. In this regard, the first first-colorlight, the second first-color light, and the third first-color light mayhave different maximum emission wavelengths from one another. The firstlight may be blue light, the first first-color light may be red light,the second first-color light may be green light, and the thirdfirst-color light may be blue light, but embodiments are not limitedthereto.

The quantum dot refers to a crystal of a semiconductor compound and mayinclude any material emitting emission wavelengths of different lengthsaccording to the size of the crystal. Accordingly, types of compoundsconstituting the quantum dot are not particularly limited.

In an embodiment, the quantum dot may include a semiconductor compoundmaterial selected from Groups III-VI semiconductor compounds, GroupsII-VI semiconductor compounds; Groups III-V semiconductor compounds;Groups IV-VI semiconductor compounds; a Group IV element or compound;and a combination thereof.

For example, the Groups III-VI semiconductor compounds may be selectedfrom: a binary compound such as In₂S₃; and a ternary compound selectedfrom AgInS, AgInS₂, CuInS, CuInS₂, and any mixture thereof, butembodiments are not limited thereto.

For example, the Groups II-VI semiconductor compounds may be selectedfrom a binary compound selected from CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO,HgS, HgSe, HgTe, MgSe, MgS, and any mixture thereof; a ternary compoundselected from CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe,HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe,HgZnTe, MgZnSe, MgZnS, any mixture thereof; and a quaternary compoundselected from CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe,HgZnSeS, HgZnSeTe, HgZnSTe, and any mixture thereof, but embodiments arenot limited thereto.

For example, the Groups III-V semiconductor compounds may be selectedfrom: a binary compound selected from GaN, GaP, GaAs, GaSb, AlN, AlP,AlAs, AlSb, InN, InP, InAs, InSb, and any mixture thereof; a ternarycompound selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs,AlNSb, AlPAs, AlPSb, InGaP, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP,and any mixture thereof; and a quaternary compound selected fromGaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs,GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and any mixturethereof, but embodiments are not limited thereto.

For example, the Groups IV-VI semiconductor compounds may be selectedfrom: a binary compound selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe,and any mixture thereof; a ternary compound selected from SnSeS, SnSeTe,SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and any mixturethereof; and a quaternary compound selected from SnPbSSe, SnPbSeTe,SnPbSTe, and any mixture thereof, but embodiments are not limitedthereto.

For example, the Group IV element or compound may be selected from: asingle element compound selected from Si, Ge, and any mixture thereof;and a binary compound selected from SiC, SiGe, and any mixture thereof,but embodiments are not limited thereto.

The binary compound, the ternary compound, or the quaternary compoundmay exist in particles at uniform concentration, or may exist in thesame particle in a state in which a concentration distribution isdifferent.

The quantum dot may have a uniform single structure or a doublecore-shell structure. For example, the core-shell may include differentmaterials. For example, materials constituting each of the core and theshell may include different semiconductor compounds.

The shell of the quantum dot may serve as a protective layer formaintaining semiconductor characteristics by preventing chemicaldegeneration of the core and/or may serve as a charging layer forimparting electrophoretic characteristics to the quantum dot. The shellmay be a single layer or a multilayer. An interface between the core andthe shell may have a concentration gradient in which the concentrationof elements existing in the shell decreases toward the center.

Examples of the shell of the quantum dot may include a metal ornon-metal oxide, a semiconductor compound, or any combination thereof.For example, the metal or non-metal oxide may include a binary compound,such as SiO₂, Al₂O₃, TiO₂, ZnO, MnO, Mn₂O₃, Mn₃O₄, CuO, FeO, Fe₂O₃,Fe₃O₄, CoO, Co₃O₄, or NiO, or a ternary compound, such as MgAl₂O₄,CoFe₂O₄, NiFe₂O₄, or CoMn₂O₄, but embodiments are not limited thereto.The semiconductor compound may include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe,ZnSeS, ZnTeS, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InGaP, InSb,AlAs, AlP, AlSb, and the like, but embodiments are not limited thereto.

A diameter of the quantum dot is not particularly limited, but may be,for example, in a range of about 1 nm to about 10 nm. By adjusting thesize of the quantum dot, the energy band gap may also be adjusted,thereby obtaining light of various wavelengths in the quantum dotemission layer. Therefore, by using quantum dots of different sizes, adisplay that emits light of various wavelengths may be implemented.

The size of the quantum dot may be selected to emit red, green, and bluelight, so as to constitute a color display. The size of the quantum dotmay be configured by combining light of various colors, so as to emitwhite light.

The quantum dot may be a spherical, pyramidal, multi-arm, or cubicnanoparticle, nanotube, nanowire, nanofiber, or nanoplate particle, butembodiments are not limited thereto.

A full width of half maximum (FWHM) of an emission wavelength spectrumof the quantum dot may be about 45 nm or less. For example, a full widthof half maximum of an emission wavelength spectrum of the quantum dotmay be about 40 nm or less. For example, a full width of half maximum ofan emission wavelength spectrum of the quantum dot may be about 30 nm orless. When the FWHM of the emission wavelength spectrum of the quantumdot is within this range, color purity or color reproduction may beimproved. Light emitted through such a quantum dot is irradiatedomnidirectionally, thereby providing a wide viewing angle.

The quantum dot may be synthesized by a wet chemical process, anorganometallic chemical vapor deposition process, a molecular beamepitaxy process, or a similar process.

According to the wet chemical process, a precursor material is added toan organic solvent to grow a particle crystal. When the crystal grows,the organic solvent serves as a dispersant naturally coordinated to thesurface of the quantum dot crystal and controls the growth of thecrystal. In this regard, the wet chemical process may be easilyperformed compared to a vapor deposition process, such as metal organicchemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), andthrough a low-cost process, the growth of inorganic nanoparticles may becontrolled.

The first color filter area, the second color filter area, and the thirdcolor filter area may each include a scattering component, butembodiments are not limited thereto.

The light-emitting apparatus may further include a thin-film transistorin addition to the light-emitting device 1 as described above. Thethin-film transistor may include a source electrode, a drain electrode,and an activation layer, wherein any one of the source electrode and thedrain electrode may be electrically connected to any one of the firstelectrode and the second electrode of the light-emitting device.

The thin-film transistor may further include a gate electrode, a gateinsulation layer, or the like.

The active layer may include crystalline silicon, amorphous silicon,organic semiconductor, oxide semiconductor, or the like, but embodimentsare not limited thereto.

The light-emitting apparatus may further include a sealing part forsealing the light-emitting device. The sealing part may be locatedbetween the color filter and the light-emitting device. The sealing partmay allow an image from the light-emitting device to be implemented andmay block outside air and moisture from penetrating into thelight-emitting device. The sealing part may be a sealing substrateincluding a transparent glass or a plastic substrate. The sealing partmay be a thin film encapsulation layer including organic layers and/orinorganic layers. In case that the sealing part is a thin-filmencapsulation layer, the entire display apparatus may be flexible.

The light-emitting apparatus may be used as various displays, lightsources, and the like.

[Authentication Apparatus]

The authentication apparatus may be, for example, a biometricauthentication apparatus for authenticating an individual by usingbiometric information of a biometric body (for example, a fingerprint, apupil, or the like).

The authentication apparatus may further include, in addition to thelight-emitting device, a biometric information collector.

[Electronic Apparatus]

The electronic apparatus may be applied to personal computers (forexample, a mobile personal computer), mobile phones, digital cameras,electronic organizers, electronic dictionaries, electronic gamemachines, medical instruments (for example, electronic thermometers,sphygmomanometers, blood glucose meters, pulse measurement devices,pulse wave measurement devices, electrocardiogram (ECG) displays,ultrasonic diagnostic devices, or endoscope displays), fish finders,various measuring instruments, meters (for example, meters for avehicle, an aircraft, and a vessel), projectors, and the like, butembodiments are not limited thereto.

[Preparation Method]

Layers constituting the hole transport region, an emission layer, andlayers constituting the electron transport region may be formed by usingone or more suitable methods selected from vacuum deposition, spincoating, casting, Langmuir-Blodgett (LB) deposition, ink-jet printing,laser-printing, and laser-induced thermal imaging.

In case that the layers constituting the hole transport region, anemission layer, and layers constituting the electron transport regionare formed by vacuum deposition, the deposition may be performed at adeposition temperature in a range of about 100° C. to about 500° C., avacuum degree in a range of about 10⁻⁸ torr to about 10⁻³ torr, and adeposition speed in a range of about 0.01 Å/sec to about 100 Å/sec bytaking into account a material to be included in a layer to be formedand the structure of a layer to be formed.

In case that the layers constituting the hole transport region, anemission layer, and layers constituting the electron transport regionare formed by spin coating, the spin coating may be performed at acoating speed in a range of about 2,000 rpm to about 5,000 rpm and at aheat treatment temperature in a range of about 80° C. to 200° C. bytaking into account a material to be included in a layer to be formedand the structure of a layer to be formed.

[Definitions of Substituents]

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear orbranched aliphatic saturated hydrocarbon monovalent group having 1 to 60carbon atoms, and examples thereof include a methyl group, an ethylgroup, a propyl group, an isobutyl group, a sec-butyl group, atert-butyl group, a pentyl group, an isoamyl group, and a hexyl group.The term “C₁-C₆₀ alkylene group” as used herein refers to a divalentgroup having the same structure as the C₁-C₆₀ alkyl group.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbongroup having at least one carbon-carbon double bond in the middle or atthe terminus of the C₂-C₆₀ alkyl group, and examples thereof include anethenyl group, a propenyl group, and a butenyl group. The term “C₂-C₆₀alkenylene group” as used herein refers to a divalent group having thesame structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbongroup having at least one carbon-carbon triple bond in the middle or atthe terminus of the C₂-C₆₀ alkyl group, and examples thereof include anethynyl group, and a propynyl group. The term “C₂-C₆₀ alkynylene group”as used herein refers to a divalent group having the same structure asthe C₂-C₆₀ alkynyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalentgroup represented by —OA₁₀₁ (wherein A₁₀₁ is the C₁-C₆₀ alkyl group),and examples thereof include a methoxy group, an ethoxy group, and anisopropyloxy group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalentsaturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, andexamples thereof include a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term“C₃-C₁₀ cycloalkylene group” as used herein refers to a divalent grouphaving the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein refers to amonovalent monocyclic group having at least one heteroatom selected fromN, O, Si, P, and S as a ring-forming atom and 1 to 10 carbon atoms, andexamples thereof include a 1,2,3,4-oxatriazolidinyl group, atetrahydrofuranyl group, and a tetrahydrothiophenyl group. The term“C₁-C₁₀ heterocycloalkylene group” as used herein refers to a divalentgroup having the same structure as the C₁-C₁₀ heterocycloalkyl group.

The term C₃-C₁₀ cycloalkenyl group used herein refers to a monovalentmonocyclic group that has 3 to 10 carbon atoms and at least onecarbon-carbon double bond in the ring thereof and no aromaticity, andexamples thereof include a cyclopentenyl group, a cyclohexenyl group,and a cycloheptenyl group. The term “C₃-C₁₀ cycloalkenylene group” asused herein refers to a divalent group having the same structure as theC₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein refers to amonovalent monocyclic group that has at least one heteroatom selectedfrom N, O, Si, P, and S as a ring-forming atom, 1 to 10 carbon atoms,and at least one carbon-carbon double bond in its ring. Examples of theC₁-C₁₀ heterocycloalkenyl group include a4,5-dihydro-1,2,3,4-oxatriazolyl group, a 2,3-dihydrofuranyl group, anda 2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylenegroup” as used herein refers to a divalent group having the samestructure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent grouphaving a carbocyclic aromatic system having 6 to 60 carbon atoms, and aC₆-C₆₀ arylene group used herein refers to a divalent group having acarbocyclic aromatic system having 6 to 60 carbon atoms. Examples of theC₆-C₆₀ aryl group include a phenyl group, a naphthyl group, ananthracenyl group, a phenanthrenyl group, a pyrenyl group, and achrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene groupeach include two or more rings, the two or more rings may be fused toeach other.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalentgroup having a carbocyclic aromatic system that has at least oneheteroatom selected from N, O, Si, P, and S as a ring-forming atom, inaddition to 1 to 60 carbon atoms. The term “C₁-C₆₀ heteroarylene group”as used herein refers to a divalent group having a carbocyclic aromaticsystem that has at least one heteroatom selected from N, O, Si, P, and Sas a ring-forming atom, in addition to 1 to 60 carbon atoms. Examples ofthe C₁-C₆₀ heteroaryl group include a pyridinyl group, a pyrimidinylgroup, a pyrazinyl group, a pyridazinyl group, a triazinyl group, aquinolinyl group, and an isoquinolinyl group. When the C₁-C₆₀ heteroarylgroup and the C₁-C₆₀ heteroarylene group each include two or more rings,the two or more rings may be condensed with each other.

The term “C₆-C₆₀ aryloxy group” as used herein refers to —OA₁₀₂ (whereinA₁₀₂ is the C₆-C₆₀ aryl group), and a C₆-C₆₀ arylthio group used hereinrefers to —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group).

The term “C₁-C₆₀ heteroaryloxy group” as used herein refers to —OA₁₀₄(where A₁₀₄ is the C₁-C₆₀ heteroaryl group), and the term “C₁-C₆₀heteroarylthio group” as used herein refers to —SA₁₀₅ (where A₁₀₅ is theC₁-C₆₀ heteroaryl group).

The term “monovalent non-aromatic condensed polycyclic group” as usedherein refers to a monovalent group (for example, having 8 to 60 carbonatoms) having two or more rings condensed with each other, only carbonatoms as ring-forming atoms, and no aromaticity in its entire molecularstructure. A detailed example of the monovalent non-aromatic condensedpolycyclic group is a fluorenyl group. The term “divalent non-aromaticcondensed polycyclic group” as used herein refers to a divalent grouphaving the same structure as the monovalent non-aromatic condensedpolycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” asused herein refers to a monovalent group (for example, having 1 to 60carbon atoms) having two or more rings condensed to each other, at leastone heteroatom selected from N, O, Si, P, and S, other than carbonatoms, as a ring-forming atom, and no aromaticity in its entiremolecular structure. An example of the monovalent non-aromatic condensedheteropolycyclic group is a carbazolyl group. The term “divalentnon-aromatic condensed heteropolycyclic group” as used herein refers toa divalent group having the same structure as the monovalentnon-aromatic condensed heteropolycyclic group.

The term “C₅-C₆₀ carbocyclic group” as used herein refers to amonocyclic or polycyclic group that includes only carbon as aring-forming atom and consists of 5 to 60 carbon atoms. The C₅-C₆₀carbocyclic group may be an aromatic carbocyclic group or a non-aromaticcarbocyclic group. The C₅-C₆₀ carbocyclic group may be a ring, such asbenzene, a monovalent group, such as a phenyl group, or a divalentgroup, such as a phenylene group. In embodiments, depending on thenumber of substituents connected to the C₅-C₆₀ carbocyclic group, theC₅-C₆₀ carbocyclic group may be a trivalent group or a quadrivalentgroup.

The term “C₁-C₆₀ heterocyclic group” as used herein refers to a grouphaving the same structure as the C₅-C₆₀ carbocyclic group, except thatas a ring-forming atom, at least one heteroatom selected from N, O, Si,P, and S is used in addition to carbon (the number of carbon atoms maybe in a range of 1 to 60).

At least one substituent selected from the substituted C₅-C₆₀carbocyclic group, the substituted C₁-C₆₀ heterocyclic group, thesubstituted C₃-C₁₀ cycloalkylene group, the substituted C₁-C₁₀heterocycloalkylene group, the substituted C₃-C₁₀ cycloalkenylene group,the substituted C₁-C₁₀ heterocycloalkenylene group, the substitutedC₆-C₆₀ arylene group, the substituted C₁-C₆₀ heteroarylene group, thesubstituted divalent non-aromatic condensed polycyclic group, thesubstituted divalent non-aromatic condensed heteropolycyclic group, thesubstituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group,the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxygroup, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, thesubstituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ arylgroup, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substitutedC₁-C₆₀heteroaryloxy group, the substituted C₁-C₆₀heteroarylthio group,the substituted monovalent non-aromatic condensed polycyclic group, andthe substituted monovalent non-aromatic condensed heteropolycyclic groupmay be selected from:

-   -   deuterium (-D), —F, —Cl, —Br, —I, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazino group, a        hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a        C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group;    -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl        group, and a C₁-C₆₀ alkoxy group, each substituted with at least        one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,        a cyano group, a nitro group, an amidino group, a hydrazino        group, a hydrazono group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀        heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀        heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy        group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a        C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a        monovalent non-aromatic condensed polycyclic group, a monovalent        non-aromatic condensed heteropolycyclic group,        —Si(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₁)(Q₁₂), —B(Q₁₁)(Q₁₂), —C(═O)(Q₁₁),        —S(═O)₂(Q₁₁), and —P(═O)(Q₁₁)(Q₁₂);    -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a        C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a        C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio        group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,        a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic        condensed polycyclic group, and a monovalent non-aromatic        condensed heteropolycyclic group;    -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a        C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a        C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio        group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,        a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic        condensed polycyclic group, and a monovalent non-aromatic        condensed heteropolycyclic group, each substituted with at least        one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,        a cyano group, a nitro group, an amidino group, a hydrazino        group, a hydrazono group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl        group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀        cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀        cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀        aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a        C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀        heteroarylthio group, a monovalent non-aromatic condensed        polycyclic group, a monovalent non-aromatic condensed        heteropolycyclic group, —Si(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₁)(Q₂₂),        —B(Q₂₁)(Q₂₂), —C(═O)(Q₂₁), —S(═O)₂(Q₂₁), and —P(═O)(Q₂₁)(Q₂₂);        and    -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₁)(Q₃₂), —B(Q₃₁)(Q₃₂), —C(═O)(Q₃₁),        —S(═O)₂(Q₃₁), and —P(═O)(Q₃₁)(Q₃₂),    -   wherein Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may each        independently be selected from hydrogen, deuterium, —F, —Cl,        —Br, —I, a hydroxyl group, a cyano group, a nitro group, an        amidino group, a hydrazino group, a hydrazono group, a C₁-C₆₀        alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a        C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀        heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀        heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀        heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀        heteroarylthio group, a monovalent non-aromatic condensed        polycyclic group, a monovalent non-aromatic condensed        heteropolycyclic group, a C₁-C₆₀ alkyl group substituted with at        least one selected from deuterium, —F, and a cyano group, a        C₆-C₆₀ aryl group substituted with at least one selected from        deuterium, —F, and a cyano group, a biphenyl group, and a        terphenyl group.

The term “Ph” as used herein refers to a phenyl group, the term “Me” asused herein refers to a methyl group, the term “Et” as used hereinrefers to an ethyl group, the term “ter-Bu” or “Bu^(t)” as used hereinrefers to a tert-butyl group, and the term “OMe” as used herein refersto a methoxy group.

The term “biphenyl group” as used herein refers to “a phenyl groupsubstituted with a phenyl group”. In other words, the “biphenyl group”is a substituted phenyl group having a C₆-C₆₀ aryl group as asubstituent.

The term “terphenyl group” as used herein refers to “a phenyl groupsubstituted with a biphenyl group”. In other words, the “terphenylgroup” is a substituted phenyl group having, as a substituent, a C₆-C₆₀aryl group substituted with a C₆-C₆₀ aryl group.

* and *′ as used herein, unless defined otherwise, each refer to abinding site to a neighboring atom in a corresponding formula.

Hereinafter, a compound according to embodiments and a light-emittingdevice according to embodiments will be described in detail withreference to Synthesis Examples and Examples. The phrase “B was usedinstead of A” used in describing Synthesis Examples refers to that anidentical molar equivalent of B was used in place of A.

EXAMPLES Example 1

A 15 Ω/cm² (1,200 Å) ITO glass substrate (a product of Corning Inc.) wascut to a size of 50 mm×50 mm×0.7 mm, sonicated with isopropyl alcoholand pure water each for 5 minutes, and cleaned by exposure toultraviolet rays and ozone for 30 minutes. The resultant glass substratewas loaded onto a vacuum deposition apparatus.

HAT-CN and CuI were co-deposited at a volume ratio of 97:3 on the ITOanode of the glass substrate to form a hole injection layer having athickness of 10 nm, and NPB was deposited on the hole injection layer toform a first hole transport layer having a thickness of 240 nm, and TCTAwas deposited on the first hole transport layer to form a second holetransport layer having a thickness of 5 nm. KI, CuI, Er and FD23 wereco-deposited at a volume ratio of 90:5:3:2 on the second hole transportlayer to form an emission layer having a thickness of 19 nm.

T2T was deposited on the emission layer to form a first electrontransport layer having a thickness of 5 nm, and TPM-TAZ and Liq wereco-deposited at the volume ratio of 1:1 on the first electron transportlayer to from a second electron transport layer having a thickness of 25nm. KI and Yb were co-deposited at the volume ratio of 95:5 to 90:10 onthe second electron transport layer to form an electron injection layerhaving a thickness of 1 nm to 2 nm.

Ag and Mg were co-deposited at a volume ratio of 9:1 on the electroninjection layer to form a cathode having a thickness of 14 nm, therebycompleting the manufacture of a light-emitting device.

Comparative Example 1

A light-emitting device was manufactured in the same manner as inExample 1, except that, in forming the emission layer, H18 and FD23 wereco-deposited at the volume ratio of 97:3.

Evaluation Example 1

The driving voltage, change in the driving voltage, current efficiency,lifespan, and CIE color coordinate of the light-emitting devicesmanufactured according to Example 1 and Comparative Example 1 weremeasured by using Keithley SMU 236 and a luminance meter PR650, andresults thereof are shown in Table 1. The lifespan (T₉₇) is a period oftime that was taken until the luminance (@400 nit) was reduced to 97% ofinitial luminance (100%) after a light-emitting device was driven. Thechange in the driving voltage is a difference between the initialdriving voltage and the driving voltage measured after 500 hours ofdriving the light-emitting device.

TABLE 1 Change in Emission layer Driving driving Current Lifespan ColorFirst Second Third voltage voltage efficiency (T₉₇) coordinate materialmaterial material (V) (V) (cd/A) (hr) (y) Example 1 KI and Er FD23 11.21.5 30.2 550 0.112 CuI Comparative H18 FD23 11.4 2 21.4 500 0.125Example 1

From the Table 1, it can be seen that the light-emitting device ofExample 1 may have improved efficiency and lifespan compared toComparative Example 1, and in particular, significantly improvedefficiency.

The light-emitting device has a high efficiency, and the manufacturingcosts therefor may be relatively low.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While embodiments have been describedwith reference to the figures, it will be understood by those ofordinary skill in the art that various changes in form and details maybe made therein without departing from the spirit and scope as definedby the following claims.

What is claimed is:
 1. A light-emitting device comprising: a firstelectrode; a second electrode; and an interlayer located between thefirst electrode and the second electrode, wherein the first electrode isan anode, the second electrode is a cathode, the interlayer comprises:an emission layer; and a hole transport region located between the firstelectrode and the emission layer, the emission layer comprises: a firstmaterial including an inorganic semiconductor compound, an inorganicinsulator compound, or any combination thereof; a second materialincluding a lanthanide metal; and a third material that comprises anorganic fluorescent dopant compound, an organometallic phosphorescentdopant compound, an organic delayed fluorescence dopant compound, or anycombination thereof, the hole transport region comprises a holeinjection layer, the hole injection layer comprises: a fourth material;and a fifth material, the fourth material and the fifth material aredifferent from each other, the fourth material comprises a lanthanidemetal halide, transition metal halide, a post-transition metal halide, atellurium, a lanthanide metal telluride, transition metal telluride, apost-transition metal telluride, a lanthanide metal selenide, atransition metal selenide, a post-transition metal selenide, or anycombination thereof, and wherein for the fifth material; the fifthmaterial comprises a hole transport organic compound, and a volume ratioof the fourth material to the fifth material is in a range of about 1:99to about 20:80; or the fifth material comprises a post-transition metalhalide, an alkali metal halide, an alkaline earth metal halide, alanthanum metal halide, or any combination thereof, and the volume ratioof the fourth material to the fifth material is in a range of about0:100 to about 50:50.
 2. The light-emitting device of claim 1, whereinthe first material comprises an alkali metal halide, an alkaline earthmetal halide, a lanthanide metal halide, a transition metal halide, apost-transition metal halide, a tellurium, a lanthanide metal telluride,a transition metal telluride, a post-transition metal telluride, alanthanide metal selenide, a transition metal selenide, apost-transition metal selenide, or any combination thereof, and thesecond material comprises lanthanum (La), cerium (Ce), praseodymium(Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or any combinationthereof.
 3. The light-emitting device of claim 1, wherein the firstmaterial comprises NaI, KI, RbI, CsI, NaCl, KCl, RbCl, CsCl, NaBr, KBr,RbBr, CsBr, MgI₂, CaI₂, SrI₂, BaI₂, MgCl₂, CaCl₂, SrCl₂, BaCl₂, MgBr₂,CaBr₂, SrBr₂, BaBr₂, EuI₃, YbI₃, SmI₃, TmI₃, EuI₂, YbI₂, SmI₂, TmI₂,EuCl₃, YbCl₃, SmCl₃, TmCl₃, EuBr₃, YbBr₃, SmBr₃, TmBr₃, AgI, CuI, NiI₂,CoI₂, BiI₃, PbI₂, SnI₂, Te, EuTe, YbTe, SmTe, TmTe, EuSe, YbSe, SmSe,TmSe, ZnTe, CoTe, ZnSe, CoSe, Bi₂Te₃, Bi₂Se₃, or any combinationthereof.
 4. The light-emitting device of claim 1, wherein the firstmaterial comprises KI, RbI, CsI, CuI, or any combination thereof.
 5. Thelight-emitting device of claim 1, wherein the second material comprisesYb, Tm, Sm, Eu, Er, or any combination thereof.
 6. The light-emittingdevice of claim 1, wherein a volume of the first material is greaterthan or equal to a volume of the second material.
 7. The light-emittingdevice of claim 1, wherein the hole trans ort region further comprises ahole transport layer, an electron blocking layer, or any combinationthereof, the interlayer further comprises an electron transport regionlocated between the emission layer and the second electrode, and theelection transport region comprises a hole blocking layer, an electrontransport layer, an electron injection layer, or any combinationthereof.
 8. The light-emitting device of claim 7, wherein the electroninjection layer comprises a sixth material, and the sixth materialcomprises an alkali metal halide, an alkaline earth metal halide, alanthanide metal halide, or any combination thereof.
 9. Thelight-emitting device of claim 8, wherein the electron injection layerconsists of the sixth material.
 10. The light-emitting device of claim8, wherein the electron injection layer further comprises a seventhmaterial, the sixth material and the seventh material are different fromeach other, and the seventh material comprises an alkali metal, analkaline earth metal, a lanthanide metal, or any combination thereof.11. The light-emitting device of claim 10, wherein the sixth material isrepresented by Formula X, and the seventh material is represented byFormula Y:A_(n)B_(m)  <Formula X>C  <Formula Y> wherein in Formulae X and Y, each of A and Cindependently comprise an alkali metal, an alkaline earth metal, alanthanide metal, or any combination thereof, B is a halogen, n and mare each independently an integer of 1 or more that makes the sixthmaterial neutral, and A and C are different from each other.
 12. Thelight-emitting device of claim 7, wherein the hole transport layer is indirect contact with the emission layer, the hole transport layercomprises: an eighth material; and a ninth material, the eighth materialand the ninth material are different from each other, the eighthmaterial comprises a hole transport organic compound, and the ninthmaterial comprises an alkali metal halide, an alkaline earth metalhalide, a lanthanide metal halide, or any combination thereof.
 13. Thelight-emitting device of claim 7, wherein the electron transport layeris in direct contact with the emission layer, the electron transportlayer comprises: a tenth material; and an eleventh material, the tenthmaterial and the eleventh material are different from each other, thetenth material comprises an electron transport organic compound, and theeleventh material comprises an alkali metal halide, an alkaline earthmetal halide, a lanthanide metal halide, or any combination thereof. 14.An apparatus comprising: a thin-film transistor comprising a sourceelectrode, a drain electrode, and an activation layer; and alight-emitting device of claim 1, wherein the first electrode of thelight-emitting device is electrically connected with one of the sourceelectrode and the drain electrode of the thin-film transistor.
 15. Theapparatus of claim 14, further comprising a color filter located on apath through which light from the light-emitting device is emitted.